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>

app/templates_config.py

@@ -0,0 +1,34 @@
+# app/templates_config.py
+"""
+Shared Jinja2 templates configuration.
+
+All route modules should import `templates` from here to ensure
+consistent globals (like translation function) are available.
+"""
+from pathlib import Path
+
+from fastapi.templating import Jinja2Templates
+
+from app.utils.i18n import (
+    LANGUAGE_FLAGS,
+    LANGUAGE_NAMES,
+    SUPPORTED_LANGUAGES,
+    DEFAULT_LANGUAGE,
+    create_translation_context,
+)
+
+# Templates directory
+TEMPLATES_DIR = Path(__file__).parent / "templates"
+
+# Create shared templates instance
+templates = Jinja2Templates(directory=str(TEMPLATES_DIR))
+
+# Add translation function to Jinja2 environment globals
+# This makes _() available in all templates AND macros
+_default_translator = create_translation_context(DEFAULT_LANGUAGE)
+templates.env.globals["_"] = _default_translator
+templates.env.globals["t"] = _default_translator  # Alias
+templates.env.globals["SUPPORTED_LANGUAGES"] = SUPPORTED_LANGUAGES
+templates.env.globals["DEFAULT_LANGUAGE"] = DEFAULT_LANGUAGE
+templates.env.globals["LANGUAGE_NAMES"] = LANGUAGE_NAMES
+templates.env.globals["LANGUAGE_FLAGS"] = LANGUAGE_FLAGS