perf: round 7 — photos timeline O(N²)→incremental, range-seek authz duplication, resources row-map clone

Benchmark-gated (equivalence + BEFORE/AFTER; results + reproduce commands in
benches/ROUND7.md):

- Photos timeline re-grouped + re-laid-out the whole accumulated library on
  every 60-item page (both `groups` and `photoRows` were $derived over the
  full list), Σ ≈ O(N²/60) main-thread work during a scroll. Pages arrive
  newest-first so grouping is append-only: the new PhotoTimeline
  (lib/utils/photoTimeline.ts) re-buckets only the fresh page and re-lays-out
  only changed groups, reusing untouched groups' cached rows, falling back to
  a full rebuild on any config/deletion/non-append change. The pure
  buildPhotoRows is the verbatim reference the gate holds it equal to at every
  page. 50×60 drain: 76 500 → 3 000 grouping ops (25.5x), 23.0 → 2.2 ms
  (10.6x).

- Range downloads paid authz + access-notify twice: download_file_impl
  resolves the file via get_file_with_perms, then the Range branch re-ran
  require_file + notify_file_accessed per request. Media/PDF viewers fetch
  exclusively via Range (one request per seek), so every seek in a scrub
  re-authorized an already-cleared file. Now routed through the non-perms
  get_file_range_preloaded (matching the share-landing + WebDAV range paths);
  the unused _with_perms range method is removed. The request-level gate still
  denies before the branch runs (bench asserts member granted, outsider
  denied). Per seek removed: WARM 0.67 µs, COLD 1362.66 µs — a grant-cascade
  drive-resolve query per seek for a shared-drive recipient on a cold cache.

- /api/folders/{id}/resources row→DTO mapping cloned row.name into the DTO
  though the row is owned; folders move it (fixed icons), files compute the
  name-derived icon/category classes first then move it. 500-row page:
  10.004 → 9.004 allocs/row (500 clones removed), output identical.

Deferred with rationale in ROUND7.md: thumbnail ACL-before-304 (security
posture — needs a security review, not a perf tweak), batch_operations
Arc<str>→String widening, list-view O(N²) on smaller lists, and the serial→
join! pairs (decide-by-bench with injected latency, per the round-6 rejection).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017aJu9ghvuT8WqC31ZEGTBA

src/interfaces/api/handlers/folder_handler.rs

@@ -476,7 +476,9 @@ pub async fn list_folder_resources(
                         let dto = FolderDto {
                             etag: resource_id.clone(),
                             id: resource_id,
-                            name: row.name.clone(),
+                            // Folders use fixed icon classes (below), so `name`
+                            // is never borrowed again — move it instead of cloning.
+                            name: row.name,
                             path: String::new(), // cleared — share recipients must not see hierarchy
                             parent_id: row.parent_id.map(|u| u.to_string()),
                             drive_id: row.drive_id,
@@ -514,20 +516,26 @@ pub async fn list_folder_resources(
                         } else {
                             File::compute_etag(&content_hash, modified_at_u)
                         };
+                        // Compute the name-derived icon/category classes first
+                        // (they borrow `&row.name`), so `name` can be moved into
+                        // the DTO below instead of cloned — one fewer String
+                        // alloc per file row (benches/ROUND7.md).
+                        let icon_class = intern_display(icon_class_for(&row.name, mime));
+                        let icon_special_class =
+                            intern_display(icon_special_class_for(&row.name, mime));
+                        let category = intern_display(category_for(&row.name, mime));
                         let dto = FileDto {
                             id: row.id.to_string(),
-                            name: row.name.clone(),
+                            name: row.name,
                             path: String::new(),
                             size: size_bytes,
                             mime_type: intern_mime(mime),
                             folder_id: row.parent_id.map(|u| u.to_string()),
                             created_at: row.created_at.timestamp() as u64,
                             modified_at: row.modified_at.timestamp() as u64,
-                            icon_class: intern_display(icon_class_for(&row.name, mime)),
-                            icon_special_class: intern_display(icon_special_class_for(
-                                &row.name, mime,
-                            )),
-                            category: intern_display(category_for(&row.name, mime)),
+                            icon_class,
+                            icon_special_class,
+                            category,
                             size_formatted: format_file_size(size_bytes),
                             sort_date: None,
                             content_hash,