feat: share heaps and folders with other users, fix auth and vision pipeline

Sharing:
- New HeapShare and FolderShare models with read/write permissions
- Sharing API router (CRUD for heap and folder shares)
- Heap endpoints accept shared access (photo_ids, add/remove with write)
- Photo list drops user_id filter in shared context, adds owner_username
- Media serving (thumb/original/proxy) falls back to share check on 404
- ShareDialog component for managing shares from kebab menus
- HeapsPanel shows "Shared with me" section for shared heaps
- LeftSidebar shows "Shared with me" section for shared folders
- Owner badge on PhotoThumbnail for photos from other users

Auth:
- Access token default bumped to 1 year, refresh to 10 years
- Refresh token persisted in localStorage (survives page reload)
- Timer-based refresh replaced with 401 axios interceptor

Vision pipeline fixes:
- Bootstrap sets Redis ready key even on partial export failure
- Export functions run conditionally (only for actually missing models)
- _load_thumb handles multi-user path (/data/thumbs/{user_id}/{photo_id}/)
- can_access_photo_via_share uses single subquery instead of N+1 loop

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/services/vision/bootstrap_models.py

@@ -73,21 +73,31 @@ def bootstrap(models_dir: str | None = None):
         for rel_path, desc in missing:
             logger.warning("  %s — %s", base / rel_path, desc)
 
-        try:
-            from app.services.vision import export_models
+        from app.services.vision import export_models
 
-            export_models.export_openclip(base)
-            export_models.export_siglip2(base)
-            export_models.export_yolov8n(base)
-        except Exception as e:
-            logger.error(
-                "Automatic export failed: %s. "
-                "Run `python -m app.services.vision.export_models "
-                "--models-dir %s` manually before starting the worker.",
-                e,
-                base,
-            )
-            return
+        missing_paths = {rel for rel, _ in missing}
+
+        # Only run the export functions whose outputs are actually missing.
+        # Each function is mapped to the file(s) it produces.
+        export_map = [
+            (export_models.export_openclip, ["embed/visual.onnx", "embed/textual.onnx"]),
+            (export_models.export_siglip2, ["embed_siglip2/visual.onnx", "embed_siglip2/textual.onnx"]),
+            (export_models.export_yolov8n, ["detect/yolov8n.onnx"]),
+        ]
+        for export_fn, outputs in export_map:
+            if not any(o in missing_paths for o in outputs):
+                continue
+            try:
+                export_fn(base)
+            except Exception as e:
+                logger.error(
+                    "Export step %s failed: %s. "
+                    "Run `python -m app.services.vision.export_models "
+                    "--models-dir %s` manually to retry.",
+                    export_fn.__name__,
+                    e,
+                    base,
+                )
 
         # Re-check what's still missing after the export pass.
         still_missing = [