feat: add tags/labels for saved items

- Add free-form tags per item: chip display with remove, inline add (comma-separated, grid view only), and a toolbar tag-filter popover listing every tag in use
- Search now also matches tags; tags sync across devices like every other item field
- Fix Firefox manifest.json compliance for AMO submission: replace the placeholder gecko id with a real UUID, add the now-required data_collection_permissions (bookmarksInfo, since synced items are personal browsing/bookmark data), and bump strict_min_version to 140.0 (142.0 for gecko_android) to match
- Add description.md (elevator pitch / short / detailed descriptions for store listings), PRIVACY.md, and .gitignore for the dist/ packaging output
- Reword all em-dash punctuation across docs and code comments per user preference

manifest.json

@@ -27,8 +27,14 @@
   },
   "browser_specific_settings": {
     "gecko": {
-      "id": "[email protected]",
-      "strict_min_version": "109.0"
+      "id": "{b5bcdd65-958d-4b77-a5d6-ba2684c37a94}",
+      "strict_min_version": "140.0",
+      "data_collection_permissions": {
+        "required": ["bookmarksInfo"]
+      }
+    },
+    "gecko_android": {
+      "strict_min_version": "142.0"
     }
   }
 }