perf(listing): return per-item is_favorite/is_shared, drop client badge fetches

The folder listing now carries the favorite/share badge state for exactly the
items it returns, so the files browser stops fetching favorites and outgoing
shares separately. This removes the last per-navigation badge round-trips AND
fixes the correctness hole of the previous approaches: badges were derived from
only the first 200 global favorites / shares, so a favorited or shared item
outside that window showed no badge. Now every listed item is correct, and the
work is scoped to the items on screen.

Backend (`GET /api/folders/{id}/listing`):
- `FolderListingDto` gains `favorite_ids` and `shared_ids` (sorted) — listing-
  level metadata, so no churn to the many FileDto/FolderDto constructors.
- The handler computes both with two batched, index-backed queries run
  concurrently: `FavoritesService::favorited_ids` (auth.user_favorites, ANY) and
  `PgAclEngine::shared_resource_ids` (storage.role_grants by granted_by + ANY,
  which already covers public links as 'token' grants — same membership the
  /grants/outgoing/resources endpoint exposes). Both fold into the ETag.
- Public-share browsing passes empty sets (anonymous, read-only context).

Frontend:
- `listFolder` reads `favorite_ids` / `shared_ids`; the files view seeds local
  badge sets straight from the listing and updates them optimistically on
  favorite toggle / batch / share creation (via ShareDialog's `onshared`).
- Removes the session `badges` store + its fetches entirely — the listing is now
  the single, authoritative, fetch-free source.

Net: favorite/share badges cost zero extra client requests per navigation and
are correct regardless of how many favorites/shares the user has. Validated:
cargo check + clippy -D warnings (backend; integration tests need Postgres,
unavailable here), frontend npm run check + unit tests, and a headless render of
the real files route (list + grid) with the new flags present — no errors.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01M8Vb9QHmLZnEMzHz7MrFy6

src/application/dtos/folder_listing_dto.rs

@@ -12,4 +12,11 @@ pub struct FolderListingDto {
     pub folders: Vec<FolderDto>,
     /// Files inside the requested folder
     pub files: Vec<FileDto>,
+    /// Ids (folders + files in this listing) the caller has favorited. Lets the
+    /// client render star badges without a separate per-navigation favorites
+    /// fetch. Sorted for a stable response / ETag.
+    pub favorite_ids: Vec<String>,
+    /// Ids in this listing the caller has an outgoing share/grant on (incl.
+    /// public links). Sorted for a stable response / ETag.
+    pub shared_ids: Vec<String>,
 }

src/application/services/favorites_service.rs

@@ -27,6 +27,17 @@ impl FavoritesService {
     pub fn new(repo: Arc<FavoritesPgRepository>) -> Self {
         Self { repo }
     }
+
+    /// Subset of `(item_id, item_type)` pairs the user has favorited — used to
+    /// stamp star badges onto a folder listing in one batched query (no N+1, no
+    /// global page fetch).
+    pub async fn favorited_ids(
+        &self,
+        user_id: Uuid,
+        items: &[(&str, &str)],
+    ) -> Result<HashSet<String>> {
+        self.repo.batch_check_favorites(user_id, items).await
+    }
 }
 
 impl FavoritesUseCase for FavoritesService {

src/application/services/share_browse_service.rs

@@ -186,6 +186,10 @@ impl ShareBrowseService {
         Ok(FolderListingDto {
             folders: folders_res?,
             files: files_res?,
+            // Public-share browsing is an anonymous, read-only context — no
+            // per-caller favorite/share badges apply.
+            favorite_ids: Vec::new(),
+            shared_ids: Vec::new(),
         })
     }
 }