fix: consolidate CMS page seed scripts and fix 3 bugs

- Fix `ContentPage.store_id is None` (Python identity check, always
  False) → use `.is_(None)` for proper SQLAlchemy NULL filtering
- Create pages for ALL platforms instead of only OMS
- Merge create_platform_pages.py into create_default_content_pages.py
  (5 overlapping pages, only platform_homepage was unique)
- Delete redundant create_platform_pages.py
- Update Makefile, install.py, and docs references

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/seed/create_default_content_pages.py

@@ -2,8 +2,9 @@
 """
 Create Default Platform Content Pages (CMS)
 
-This script creates platform-level default content pages that all stores inherit.
-These pages serve as the baseline content for:
+This script creates platform-level default content pages for ALL platforms.
+Pages include:
+- Platform Homepage (platform marketing page)
 - About Us
 - Contact
 - FAQ
@@ -12,14 +13,16 @@ These pages serve as the baseline content for:
 - Privacy Policy
 - Terms of Service
 
+Pages are created per-platform (unique constraint: platform_id + store_id + slug).
 Stores can override any of these pages with their own custom content.
 
 Prerequisites:
     - Database migrations must be applied
     - content_pages table must exist
+    - Platforms must exist (run init_production.py first)
 
 Usage:
-    python scripts/create_default_content_pages.py
+    python scripts/seed/create_default_content_pages.py
 
     # Or with make:
     make create-cms-defaults
@@ -59,7 +62,32 @@ from app.modules.cms.models import ContentPage
 from app.modules.tenancy.models import Platform
 
 # ============================================================================
-# DEFAULT PAGE CONTENT
+# PLATFORM HOMEPAGE (is_platform_page=True)
+# ============================================================================
+
+PLATFORM_HOMEPAGE = {
+    "slug": "platform_homepage",
+    "title": "Welcome to Our Multi-Store Marketplace",
+    "content": """
+<p class="lead">
+    Connect stores with customers worldwide. Build your online store and reach millions of shoppers.
+</p>
+<p>
+    Our platform empowers entrepreneurs to launch their own branded e-commerce stores
+    with minimal effort and maximum impact.
+</p>
+    """,
+    "meta_description": "Leading multi-store marketplace platform. Connect with thousands of stores and discover millions of products.",
+    "meta_keywords": "marketplace, multi-store, e-commerce, online shopping, platform",
+    "show_in_footer": False,
+    "show_in_header": False,
+    "is_platform_page": True,
+    "template": "modern",
+    "display_order": 0,
+}
+
+# ============================================================================
+# DEFAULT STORE CONTENT PAGES (is_platform_page=False)
 # ============================================================================
 
 DEFAULT_PAGES = [
@@ -479,9 +507,58 @@ DEFAULT_PAGES = [
 # ============================================================================
 
 
+def _page_exists(db: Session, platform_id: int, slug: str) -> bool:
+    """Check if a page already exists for the given platform and slug."""
+    existing = db.execute(
+        select(ContentPage).where(
+            ContentPage.platform_id == platform_id,
+            ContentPage.store_id.is_(None),
+            ContentPage.slug == slug,
+        )
+    ).scalar_one_or_none()
+    return existing is not None
+
+
+def _create_page(
+    db: Session, platform_id: int, page_data: dict, *, is_platform_page: bool = False
+) -> bool:
+    """Create a single content page. Returns True if created, False if skipped."""
+    slug = page_data["slug"]
+    title = page_data["title"]
+
+    if _page_exists(db, platform_id, slug):
+        print(f"    Skipped: {title} (/{slug}) - already exists")
+        return False
+
+    page = ContentPage(
+        platform_id=platform_id,
+        store_id=None,
+        slug=slug,
+        title=title,
+        content=page_data["content"],
+        content_format="html",
+        template=page_data.get("template", "default"),
+        meta_description=page_data["meta_description"],
+        meta_keywords=page_data["meta_keywords"],
+        is_platform_page=is_platform_page,
+        is_published=True,
+        published_at=datetime.now(UTC),
+        show_in_footer=page_data.get("show_in_footer", True),
+        show_in_header=page_data.get("show_in_header", False),
+        show_in_legal=page_data.get("show_in_legal", False),
+        display_order=page_data["display_order"],
+        created_at=datetime.now(UTC),
+        updated_at=datetime.now(UTC),
+    )
+
+    db.add(page)
+    print(f"    Created: {title} (/{slug})")
+    return True
+
+
 def create_default_pages(db: Session) -> None:
     """
-    Create default platform content pages.
+    Create default platform content pages for ALL platforms.
 
     This function is idempotent - it will skip pages that already exist.
     """
@@ -489,68 +566,52 @@ def create_default_pages(db: Session) -> None:
     print("Creating Default Platform Content Pages (CMS)")
     print("=" * 70 + "\n")
 
-    # Resolve OMS platform for platform_id
-    oms_platform = db.execute(
-        select(Platform).where(Platform.code == "oms")
-    ).scalar_one_or_none()
-    if not oms_platform:
-        print("  ⚠️  OMS platform not found. Run init_production.py first.")
+    # Load all platforms
+    platforms = db.execute(select(Platform)).scalars().all()
+    if not platforms:
+        print("  No platforms found. Run init_production.py first.")
         return
-    platform_id = oms_platform.id
 
-    created_count = 0
-    skipped_count = 0
+    total_created = 0
+    total_skipped = 0
 
-    for page_data in DEFAULT_PAGES:
-        # Check if page already exists (platform default with this slug)
-        existing = db.execute(
-            select(ContentPage).where(
-                ContentPage.store_id is None, ContentPage.slug == page_data["slug"]
-            )
-        ).scalar_one_or_none()
+    for platform in platforms:
+        print(f"  Platform: {platform.name} (code={platform.code})")
 
-        if existing:
-            print(
-                f"  ⏭️  Skipped: {page_data['title']} (/{page_data['slug']}) - already exists"
-            )
+        created_count = 0
+        skipped_count = 0
+
+        # Create platform homepage
+        if _create_page(db, platform.id, PLATFORM_HOMEPAGE, is_platform_page=True):
+            created_count += 1
+        else:
             skipped_count += 1
-            continue
 
-        # Create new platform default page
-        page = ContentPage(
-            platform_id=platform_id,
-            store_id=None,  # Platform default
-            slug=page_data["slug"],
-            title=page_data["title"],
-            content=page_data["content"],
-            content_format="html",
-            meta_description=page_data["meta_description"],
-            meta_keywords=page_data["meta_keywords"],
-            is_published=True,
-            published_at=datetime.now(UTC),
-            show_in_footer=page_data.get("show_in_footer", True),
-            show_in_header=page_data.get("show_in_header", False),
-            show_in_legal=page_data.get("show_in_legal", False),
-            display_order=page_data["display_order"],
-            created_at=datetime.now(UTC),
-            updated_at=datetime.now(UTC),
-        )
+        # Create default store content pages
+        for page_data in DEFAULT_PAGES:
+            if _create_page(db, platform.id, page_data):
+                created_count += 1
+            else:
+                skipped_count += 1
 
-        db.add(page)
-        print(f"  ✅ Created: {page_data['title']} (/{page_data['slug']})")
-        created_count += 1
+        print(f"    --- {created_count} created, {skipped_count} skipped")
+        print()
+
+        total_created += created_count
+        total_skipped += skipped_count
 
     db.commit()
 
-    print("\n" + "=" * 70)
+    print("=" * 70)
     print("Summary:")
-    print(f"  Created: {created_count} pages")
-    print(f"  Skipped: {skipped_count} pages (already exist)")
-    print(f"  Total:   {created_count + skipped_count} pages")
+    print(f"  Platforms: {len(platforms)}")
+    print(f"  Created:   {total_created} pages")
+    print(f"  Skipped:   {total_skipped} pages (already exist)")
+    print(f"  Total:     {total_created + total_skipped} pages")
     print("=" * 70 + "\n")
 
-    if created_count > 0:
-        print("✅ Default platform content pages created successfully!\n")
+    if total_created > 0:
+        print("Default platform content pages created successfully!\n")
         print("Next steps:")
         print(
             "  1. View pages at: /about, /contact, /faq, /shipping, /returns, /privacy, /terms"
@@ -558,7 +619,7 @@ def create_default_pages(db: Session) -> None:
         print("  2. Stores can override these pages through the store dashboard")
         print("  3. Edit platform defaults through the admin panel\n")
     else:
-        print("ℹ️  All default pages already exist. No changes made.\n")
+        print("All default pages already exist. No changes made.\n")
 
 
 # ============================================================================
@@ -568,14 +629,14 @@ def create_default_pages(db: Session) -> None:
 
 def main():
     """Main execution function."""
-    print("\n🚀 Starting Default Content Pages Creation Script...\n")
+    print("\nStarting Default Content Pages Creation Script...\n")
 
     db = SessionLocal()
     try:
         create_default_pages(db)
-        print("✅ Script completed successfully!\n")
+        print("Script completed successfully!\n")
     except Exception as e:
-        print(f"\n❌ Error: {e}\n")
+        print(f"\nError: {e}\n")
         db.rollback()
         raise
     finally: