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/admin/settings.py

@@ -15,6 +15,7 @@ from sqlalchemy.orm import Session
 
 from app.api.deps import get_current_admin_api
 from app.core.database import get_db
+from app.exceptions import ConfirmationRequiredException, ResourceNotFoundException
 from app.services.admin_audit_service import admin_audit_service
 from app.services.admin_settings_service import admin_settings_service
 from models.database.user import User
@@ -78,9 +79,9 @@ def get_setting(
     setting = admin_settings_service.get_setting_by_key(db, key)
 
     if not setting:
-        from fastapi import HTTPException
-
-        raise HTTPException(status_code=404, detail=f"Setting '{key}' not found")
+        raise ResourceNotFoundException(
+            resource_type="Setting", identifier=key
+        )
 
     return AdminSettingResponse.model_validate(setting)
 
@@ -184,12 +185,10 @@ def delete_setting(
     Requires confirmation parameter.
     WARNING: Deleting settings may affect platform functionality.
     """
-    from fastapi import HTTPException
-
     if not confirm:
-        raise HTTPException(
-            status_code=400,
-            detail="Deletion requires confirmation parameter: confirm=true",
+        raise ConfirmationRequiredException(
+            operation="delete_setting",
+            message="Deletion requires confirmation parameter: confirm=true",
         )
 
     message = admin_settings_service.delete_setting(