feat: add module definition completeness validation and permissions

Add new validation rules MOD-020 to MOD-023 for module definition
completeness and standardize permissions across all modules.

Changes:
- Add MOD-020: Module definitions must have required attributes
- Add MOD-021: Modules with menus should have features
- Add MOD-022: Feature modules should have permissions
- Add MOD-023: Modules with routers should use get_*_with_routers pattern

Module permissions added:
- analytics: view, export, manage_dashboards
- billing: view_tiers, manage_tiers, view_subscriptions, manage_subscriptions, view_invoices
- cart: view, manage
- checkout: view_settings, manage_settings
- cms: view_pages, manage_pages, view_media, manage_media, manage_themes
- loyalty: view_programs, manage_programs, view_rewards, manage_rewards
- marketplace: view_integration, manage_integration, sync_products
- messaging: view_messages, send_messages, manage_templates
- payments: view_gateways, manage_gateways, view_transactions

Module improvements:
- Complete cart module with features and permissions
- Complete checkout module with features and permissions
- Add features to catalog module
- Add version to cms module
- Fix loyalty platform_router attachment
- Add path definitions to payments module
- Remove empty scheduled_tasks from dev_tools module

Documentation:
- Update module-system.md with new validation rules
- Update architecture-rules.md with MOD-020 to MOD-023

Tests:
- Add unit tests for module definition completeness
- Add tests for permission structure validation

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

app/modules/billing/routes/pages/platform.py

@@ -0,0 +1,121 @@
+# app/modules/billing/routes/pages/public.py
+"""
+Billing Public Page Routes (HTML rendering).
+
+Public (unauthenticated) pages for pricing and signup:
+- Pricing page
+- Signup wizard
+- Signup success
+"""
+
+from fastapi import APIRouter, Depends, Request
+from fastapi.responses import HTMLResponse
+from sqlalchemy.orm import Session
+
+from app.core.database import get_db
+from app.modules.billing.models import TIER_LIMITS, TierCode
+from app.modules.core.utils.page_context import get_public_context
+from app.templates_config import templates
+
+router = APIRouter()
+
+
+def _get_tiers_data() -> list[dict]:
+    """Build tier data for display in templates."""
+    tiers = []
+    for tier_code, limits in TIER_LIMITS.items():
+        tiers.append(
+            {
+                "code": tier_code.value,
+                "name": limits["name"],
+                "price_monthly": limits["price_monthly_cents"] / 100,
+                "price_annual": (limits["price_annual_cents"] / 100)
+                if limits.get("price_annual_cents")
+                else None,
+                "orders_per_month": limits.get("orders_per_month"),
+                "products_limit": limits.get("products_limit"),
+                "team_members": limits.get("team_members"),
+                "order_history_months": limits.get("order_history_months"),
+                "features": limits.get("features", []),
+                "is_popular": tier_code == TierCode.PROFESSIONAL,
+                "is_enterprise": tier_code == TierCode.ENTERPRISE,
+            }
+        )
+    return tiers
+
+
+# ============================================================================
+# PRICING PAGE
+# ============================================================================
+
+
+@router.get("/pricing", response_class=HTMLResponse, name="platform_pricing")
+async def pricing_page(
+    request: Request,
+    db: Session = Depends(get_db),
+):
+    """
+    Standalone pricing page with detailed tier comparison.
+    """
+    context = get_public_context(request, db)
+    context["tiers"] = _get_tiers_data()
+    context["page_title"] = "Pricing"
+
+    return templates.TemplateResponse(
+        "billing/public/pricing.html",
+        context,
+    )
+
+
+# ============================================================================
+# SIGNUP WIZARD
+# ============================================================================
+
+
+@router.get("/signup", response_class=HTMLResponse, name="platform_signup")
+async def signup_page(
+    request: Request,
+    tier: str | None = None,
+    annual: bool = False,
+    db: Session = Depends(get_db),
+):
+    """
+    Multi-step signup wizard.
+
+    Query params:
+    - tier: Pre-selected tier code
+    - annual: Pre-select annual billing
+    """
+    context = get_public_context(request, db)
+    context["page_title"] = "Start Your Free Trial"
+    context["selected_tier"] = tier
+    context["is_annual"] = annual
+    context["tiers"] = _get_tiers_data()
+
+    return templates.TemplateResponse(
+        "billing/public/signup.html",
+        context,
+    )
+
+
+@router.get(
+    "/signup/success", response_class=HTMLResponse, name="platform_signup_success"
+)
+async def signup_success_page(
+    request: Request,
+    vendor_code: str | None = None,
+    db: Session = Depends(get_db),
+):
+    """
+    Signup success page.
+
+    Shown after successful account creation.
+    """
+    context = get_public_context(request, db)
+    context["page_title"] = "Welcome to Wizamart!"
+    context["vendor_code"] = vendor_code
+
+    return templates.TemplateResponse(
+        "billing/public/signup-success.html",
+        context,
+    )