refactor: migrate vendor APIs to token-based context and consolidate architecture

## Vendor-in-Token Architecture (Complete Migration)
- Migrate all vendor API endpoints from require_vendor_context() to token_vendor_id
- Update permission dependencies to extract vendor from JWT token
- Add vendor exceptions: VendorAccessDeniedException, VendorOwnerOnlyException,
  InsufficientVendorPermissionsException
- Shop endpoints retain require_vendor_context() for URL-based detection
- Add AUTH-004 architecture rule enforcing vendor context patterns
- Fix marketplace router missing /marketplace prefix

## Exception Pattern Fixes (API-003/API-004)
- Services raise domain exceptions, endpoints let them bubble up
- Add code_quality and content_page exception modules
- Move business logic from endpoints to services (admin, auth, content_page)
- Fix exception handling in admin, shop, and vendor endpoints

## Tailwind CSS Consolidation
- Consolidate CSS to per-area files (admin, vendor, shop, platform)
- Remove shared/cdn-fallback.html and shared/css/tailwind.min.css
- Update all templates to use area-specific Tailwind output files
- Remove Node.js config (package.json, postcss.config.js, tailwind.config.js)

## Documentation & Cleanup
- Update vendor-in-token-architecture.md with completed migration status
- Update architecture-rules.md with new rules
- Move migration docs to docs/development/migration/
- Remove duplicate/obsolete documentation files
- Merge pytest.ini settings into pyproject.toml

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/api/v1/shop/content_pages.py

@@ -8,7 +8,7 @@ No authentication required.
 
 import logging
 
-from fastapi import APIRouter, Depends, HTTPException, Request
+from fastapi import APIRouter, Depends, Request
 from pydantic import BaseModel
 from sqlalchemy.orm import Session
 
@@ -90,16 +90,13 @@ def get_content_page(slug: str, request: Request, db: Session = Depends(get_db))
     vendor = getattr(request.state, "vendor", None)
     vendor_id = vendor.id if vendor else None
 
-    page = content_page_service.get_page_for_vendor(
+    page = content_page_service.get_page_for_vendor_or_raise(
         db,
         slug=slug,
         vendor_id=vendor_id,
         include_unpublished=False,  # Only show published pages
     )
 
-    if not page:
-        raise HTTPException(status_code=404, detail=f"Content page not found: {slug}")
-
     return {
         "slug": page.slug,
         "title": page.title,