feat: add platform detail/edit admin UI and service enhancements

- Add platform detail and edit admin pages with templates and JS
- Add ContentPageService methods: list_all_platform_pages, list_all_vendor_defaults
- Deprecate /admin/platform-homepage route (redirects to /admin/platforms)
- Add migration to fix content_page nullable columns
- Refine platform and vendor context middleware
- Add platform context middleware unit tests
- Update platforms.js with improved functionality
- Add section-based homepage plan documentation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

alembic/versions/z4e5f6a7b8c9_add_multi_platform_support.py

@@ -178,9 +178,7 @@ def upgrade() -> None:
         """)
     )
 
-    # Get the OMS platform ID
-    result = conn.execute(sa.text("SELECT id FROM platforms WHERE code = 'oms'"))
-    oms_platform_id = result.fetchone()[0]
+I dn
 
     # =========================================================================
     # 6. Backfill content_pages with platform_id

alembic/versions/z7h8i9j0k1l2_fix_content_page_nullable_columns.py

@@ -0,0 +1,115 @@
+"""Fix content_page nullable boolean columns
+
+Revision ID: z7h8i9j0k1l2
+Revises: z6g7h8i9j0k1
+Create Date: 2026-01-20
+
+This migration:
+1. Sets NULL values to defaults for boolean and integer columns
+2. Alters columns to be NOT NULL
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = "z7h8i9j0k1l2"
+down_revision = "z6g7h8i9j0k1"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # First, update any NULL values to defaults
+    op.execute("""
+        UPDATE content_pages
+        SET display_order = 0
+        WHERE display_order IS NULL
+    """)
+
+    op.execute("""
+        UPDATE content_pages
+        SET show_in_footer = true
+        WHERE show_in_footer IS NULL
+    """)
+
+    op.execute("""
+        UPDATE content_pages
+        SET show_in_header = false
+        WHERE show_in_header IS NULL
+    """)
+
+    op.execute("""
+        UPDATE content_pages
+        SET show_in_legal = false
+        WHERE show_in_legal IS NULL
+    """)
+
+    # Now alter columns to be NOT NULL
+    op.alter_column(
+        "content_pages",
+        "display_order",
+        existing_type=sa.Integer(),
+        nullable=False,
+        server_default="0",
+    )
+
+    op.alter_column(
+        "content_pages",
+        "show_in_footer",
+        existing_type=sa.Boolean(),
+        nullable=False,
+        server_default="true",
+    )
+
+    op.alter_column(
+        "content_pages",
+        "show_in_header",
+        existing_type=sa.Boolean(),
+        nullable=False,
+        server_default="false",
+    )
+
+    op.alter_column(
+        "content_pages",
+        "show_in_legal",
+        existing_type=sa.Boolean(),
+        nullable=False,
+        server_default="false",
+    )
+
+
+def downgrade() -> None:
+    # Revert columns to nullable (no server default)
+    op.alter_column(
+        "content_pages",
+        "display_order",
+        existing_type=sa.Integer(),
+        nullable=True,
+        server_default=None,
+    )
+
+    op.alter_column(
+        "content_pages",
+        "show_in_footer",
+        existing_type=sa.Boolean(),
+        nullable=True,
+        server_default=None,
+    )
+
+    op.alter_column(
+        "content_pages",
+        "show_in_header",
+        existing_type=sa.Boolean(),
+        nullable=True,
+        server_default=None,
+    )
+
+    op.alter_column(
+        "content_pages",
+        "show_in_legal",
+        existing_type=sa.Boolean(),
+        nullable=True,
+        server_default=None,
+    )