fix: Container width setting now applies correctly + Rail Ads improvements

- Fix container width not applying: css-global-responsive.css now uses
  CSS variable --roi-container-width instead of hardcoded values
- Add 8 Rail format options: slim-small (160x300), slim-medium (160x400),
  slim-large (160x500), skyscraper (160x600), slim-xlarge (160x700),
  wide-skyscraper (160x800), half-page (300x600), large-skyscraper (300x1050)
- Change rail_top_offset from text input to select with preset values
- Fix Rail Ads JavaScript positioning (moved after HTML, added retries)
- ThemeSettingsRenderer now always outputs CSS variables for layout

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

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

Schemas/adsense-placement.json

@@ -226,7 +226,11 @@
           "default": "skyscraper",
           "editable": true,
           "options": {
+            "slim-small": "Slim Small (160x300)",
+            "slim-medium": "Slim Medium (160x400)",
+            "slim-large": "Slim Large (160x500)",
             "skyscraper": "Skyscraper (160x600)",
+            "slim-xlarge": "Slim XLarge (160x700)",
             "wide-skyscraper": "Wide Skyscraper (160x800)",
             "half-page": "Half Page (300x600)",
             "large-skyscraper": "Large Skyscraper (300x1050)"