feat(bulk): consensus ML suggestions + frontend polish

Bulk editor now loads consensus ML suggestions across the current
selection via a new POST /api/suggestions/bulk endpoint, powered by
get_bulk_suggestions() in tag_suggestions.py. A tag is surfaced only if
it was suggested for or already applied to >= 80% of the selection;
coverage counts include images that already have the tag so a near-
universal tag isn't penalized for dropping out of suggestion lists.
Accept-only chips (no reject) match the rest of the suggestions UX.

Frontend polish in the same commit:
- Showcase session dedup (exclude seen ids, reset on second lap) and
  aspect-ratio-aware placeholder heights for better column balancing
- Modal touch-swipe navigation on the image wrapper, auto-focus of the
  tag input on desktop (>=768px), and autocomplete flip-up when the
  dropdown would cover the Suggestions section
- Settings template inline styles replaced with utility classes
- Inline series-editor script extracted to gallery-series-editor.js

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/main.py

@@ -95,6 +95,8 @@ def random_images_api():
             'thumb_url': url_for('main.serve_image', filename=thumb_path),
             'full_url': url_for('main.serve_image', filename=full_path),
             'is_video': is_video,
+            'width': img.width,
+            'height': img.height,
             'date': (img.taken_at or img.imported_at).strftime('%Y-%m-%d') if (img.taken_at or img.imported_at) else '',
             'tags': [{'name': t.name, 'kind': t.kind} for t in img.tags]
         })
@@ -714,6 +716,34 @@ def get_image_suggestions(image_id):
     return jsonify({'ok': True, 'suggestions': suggestions})
 
 
+@main.post("/api/suggestions/bulk")
+def get_bulk_suggestions_api():
+    """Consensus ML suggestions across a selection of images.
+
+    Body: {"image_ids": [...], "threshold": 0.8}
+    Returns grouped suggestions where each tag was suggested for or already
+    applied to at least `threshold` fraction of the selected images.
+    """
+    from app.services.tag_suggestions import get_bulk_suggestions
+    payload = request.get_json(force=True, silent=True) or {}
+    image_ids = payload.get('image_ids') or []
+    try:
+        image_ids = [int(x) for x in image_ids]
+    except (TypeError, ValueError):
+        return jsonify({'ok': False, 'error': 'invalid_image_ids'}), 400
+    if not image_ids:
+        return jsonify({'ok': False, 'error': 'no_image_ids'}), 400
+
+    try:
+        threshold = float(payload.get('threshold', 0.8))
+    except (TypeError, ValueError):
+        threshold = 0.8
+    threshold = max(0.0, min(1.0, threshold))
+
+    suggestions = get_bulk_suggestions(image_ids, threshold=threshold)
+    return jsonify({'ok': True, 'suggestions': suggestions, 'evaluated': len(image_ids), 'threshold': threshold})
+
+
 @main.post("/image/<int:image_id>/suggestions/accept")
 def accept_image_suggestion(image_id):
     from app.models import SuggestionFeedback