feat: complete CMS as fully autonomous self-contained module

Transform CMS from a thin wrapper into a fully self-contained module with
all code living within app/modules/cms/:

Module Structure:
- models/: ContentPage model (canonical location with dynamic discovery)
- schemas/: Pydantic schemas for API validation
- services/: ContentPageService business logic
- exceptions/: Module-specific exceptions
- routes/api/: REST API endpoints (admin, vendor, shop)
- routes/pages/: HTML page routes (admin, vendor)
- templates/cms/: Jinja2 templates (namespaced)
- static/: JavaScript files (admin/vendor)
- locales/: i18n translations (en, fr, de, lb)

Key Changes:
- Move ContentPage model to module with dynamic model discovery
- Create Pydantic schemas package for request/response validation
- Extract API routes from app/api/v1/*/ to module
- Extract page routes from admin_pages.py/vendor_pages.py to module
- Move static JS files to module with dedicated mount point
- Update templates to use cms_static for module assets
- Add module static file mounting in main.py
- Delete old scattered files (no shims - hard errors on old imports)

This establishes the pattern for migrating other modules to be
fully autonomous and independently deployable.

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

app/modules/cms/routes/api/shop.py

@@ -0,0 +1,84 @@
+# app/modules/cms/routes/api/shop.py
+"""
+Shop Content Pages API (Public)
+
+Public endpoints for retrieving content pages in shop frontend.
+No authentication required.
+"""
+
+import logging
+
+from fastapi import APIRouter, Depends, Request
+from sqlalchemy.orm import Session
+
+from app.core.database import get_db
+from app.modules.cms.schemas import (
+    PublicContentPageResponse,
+    ContentPageListItem,
+)
+from app.modules.cms.services import content_page_service
+
+router = APIRouter()
+logger = logging.getLogger(__name__)
+
+
+# ============================================================================
+# PUBLIC ENDPOINTS
+# ============================================================================
+
+
+@router.get("/navigation", response_model=list[ContentPageListItem])
+def get_navigation_pages(request: Request, db: Session = Depends(get_db)):
+    """
+    Get list of content pages for navigation (footer/header).
+
+    Uses vendor from request.state (set by middleware).
+    Returns vendor overrides + platform defaults.
+    """
+    vendor = getattr(request.state, "vendor", None)
+    vendor_id = vendor.id if vendor else None
+
+    # Get all published pages for this vendor
+    pages = content_page_service.list_pages_for_vendor(
+        db, vendor_id=vendor_id, include_unpublished=False
+    )
+
+    return [
+        {
+            "slug": page.slug,
+            "title": page.title,
+            "show_in_footer": page.show_in_footer,
+            "show_in_header": page.show_in_header,
+            "display_order": page.display_order,
+        }
+        for page in pages
+    ]
+
+
+@router.get("/{slug}", response_model=PublicContentPageResponse)
+def get_content_page(slug: str, request: Request, db: Session = Depends(get_db)):
+    """
+    Get a specific content page by slug.
+
+    Uses vendor from request.state (set by middleware).
+    Returns vendor override if exists, otherwise platform default.
+    """
+    vendor = getattr(request.state, "vendor", None)
+    vendor_id = vendor.id if vendor else None
+
+    page = content_page_service.get_page_for_vendor_or_raise(
+        db,
+        slug=slug,
+        vendor_id=vendor_id,
+        include_unpublished=False,  # Only show published pages
+    )
+
+    return {
+        "slug": page.slug,
+        "title": page.title,
+        "content": page.content,
+        "content_format": page.content_format,
+        "meta_description": page.meta_description,
+        "meta_keywords": page.meta_keywords,
+        "published_at": page.published_at.isoformat() if page.published_at else None,
+    }