fix: resolve homepage sections editor and rendering issues

- Fix sections editor not showing by converting isHomepage getter to property
- Add Alpine Collapse plugin for accordion animations
- Fix Quill editor content not syncing after page load
- Add platform dropdown to content page edit form
- Create shared templates config (app/templates_config.py) with i18n globals
  to make _() translation function available in Jinja2 macros
- Fix pricing template field names (monthly_price → price_monthly)
- Fix translation key (pricing.save_20 → pricing.save_months)
- Add tiers context to CMS homepage route for pricing section
- Fix architecture validation issues (language defaults, inline SVGs → $icon)

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

main.py

@@ -88,8 +88,8 @@ app = FastAPI(
     lifespan=lifespan,
 )
 
-# Configure Jinja2 Templates
-templates = Jinja2Templates(directory=str(TEMPLATES_DIR))
+# Configure Jinja2 Templates (shared instance with i18n globals)
+from app.templates_config import templates  # noqa: F401 - re-exported for compatibility
 
 # Setup custom exception handlers (unified approach)
 setup_exception_handlers(app)