Major refactor: deduplicate routes, sync, JS, and fix bugs

- Extract 8 common route patterns into factory functions in routes/shared.py
  (favourite, upload, replace cover, save defaults, clone, save JSON,
  get missing, clear covers) — removes ~1,100 lines across 9 route files
- Extract generic _sync_category() in sync.py — 7 sync functions become
  one-liner wrappers, removing ~350 lines
- Extract shared detail page JS into static/js/detail-common.js — all 9
  detail templates now call initDetailPage() with minimal config
- Extract layout inline JS into static/js/layout-utils.js (~185 lines)
- Extract library toolbar JS into static/js/library-toolbar.js
- Fix finalize missing-image bug: raise RuntimeError instead of logging
  warning so job is marked failed
- Fix missing scheduler default in _default_checkpoint_data()
- Fix N+1 query in Character.get_available_outfits() with batch IN query
- Convert all print() to logger across services and routes
- Add missing tags display to styles, scenes, detailers, checkpoints detail
- Update delete buttons to use trash.png icon with solid red background
- Update CLAUDE.md to reflect new architecture

Net reduction: ~1,600 lines

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

static/js/gallery/gallery-core.js

@@ -307,11 +307,24 @@
     applyGrid() {
       const container = state.dom.container;
       if (!container) return;
-      
-      // Reset any custom positioning
+
+      // Reset container styles set by other layouts
+      container.style.height = '';
+      container.style.position = '';
+      container.style.gap = '';
+
+      // Reset any custom positioning on cards and their children
       state.images.forEach(img => {
         if (img.element) {
           img.element.style.cssText = '';
+
+          // Reset child element inline styles set by mosaic/other layouts
+          const imgEl = img.element.querySelector('img');
+          if (imgEl) imgEl.style.cssText = '';
+          const badge = img.element.querySelector('.cat-badge');
+          if (badge) badge.style.cssText = '';
+          const overlay = img.element.querySelector('.overlay');
+          if (overlay) overlay.style.cssText = '';
         }
       });
     },