perf: round 10 — auth alloc purge, parent-herd batching, query-shape pack, NC 304s

Benchmark-gated (benches/ROUND10.md; every change carries a BEFORE/AFTER
harness with equivalence/safety gates — two designs were rejected or
rewritten by their own benches before adoption):

- Auth hot path: TokenClaims/CurrentUser display fields to Arc<str>, role
  to inline SmolStr end-to-end (Bearer, cookie, Basic-auth cache) — 4→1
  allocs per authenticated request, 3→0 per warm DAV request; JWT
  Encoding/Decoding/Validation built once.
- Cold shared-album herd: leader-inline parent batching in PgAclEngine
  (+ cascade try_get_with single-flight) — 100→2 parent queries per
  100-thumb cold herd, herd wall 1.9x, sequential + warm paths unchanged,
  all ROUND8/9 safety gates plus new herd-equivalence gates.
- Query-shape pack: share download double-fetch 2→1 (2.18x), contact-group
  COUNT(*) 14.9x, save_faces UNNEST 3.9x, playlist reorder UNNEST 63.7x
  (now atomic), search files∥folders join! 1.45x, move drive-lookup join!
  2.14x, trash partial (drive_id, trashed_at) indexes, CalDAV event-gate
  narrow read, favorites/recents binary-decode port, dead count_files
  removed.
- NC surface: preview + avatar honour If-None-Match (e2e: 5 KB and 197 KB
  → 0 bytes per revalidation), avatar WebP→PNG transcode memoised,
  PROPFIND/trashbin integer+date emits on stack formatters, folder-header
  enrichment join!, chunk-PUT retry stat folded into create_new open.
- common::fmt integer rendering rewritten on the std 2-digit LUT after the
  round's own bench caught the div-loop losing to to_string (16.1 ns vs
  22.5; speeds every prior-round call site).
- Micro-pack: WebDAV scope probe borrow-only, ShareService base_url
  snapshot, cookie_secure OnceLock, Arc'd AES-GCM cipher, stack request-id,
  tantivy analyzer clone dropped.
- SPA: search stale-guard + AbortController (10→1 completed round-trips,
  stale-clobber gone), getFolder in-flight dedup, gridColumns matchMedia
  hoist (10k→0 style reads).

Backend: cargo fmt + clippy -D warnings clean, 524 tests green.
Frontend: npm run check clean, 301 vitest green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018DdM7V7M3QPW7HEHg3gLov

frontend/src/routes/search/+page.svelte

@@ -124,11 +124,25 @@
 		{ v: 'size', l: t('search.sort.smallest', 'Smallest') }
 	];
 
+	// Stale-response guard: rapid-fire query/filter/sort changes each start a
+	// full recursive backend search; without the token a SLOW earlier response
+	// could resolve after (and clobber) a newer one, and the superseded server
+	// work ran to completion. The seq token keeps only the latest result; the
+	// AbortController cancels the superseded request outright.
+	let runSeq = 0;
+	let inflight: AbortController | null = null;
+
 	async function run(q: string) {
+		const seq = ++runSeq;
+		inflight?.abort();
+		inflight = null;
 		if (!q) {
 			results = null;
+			loading = false;
 			return;
 		}
+		const ctl = new AbortController();
+		inflight = ctl;
 		loading = true;
 		error = null;
 		try {
@@ -137,18 +151,23 @@
 				scope === 'folder' && filesStore.section !== 'trash'
 					? (filesStore.currentFolder ?? undefined)
 					: undefined;
-			results = await searchFiles(q, {
+			const fresh = await searchFiles(q, {
 				recursive: true,
 				sortBy,
 				folderId,
 				fileTypes: typeFilter === 'all' ? undefined : TYPE_EXT[typeFilter],
 				...sizeBounds(sizeFilter),
-				modifiedAfter: dateBound(dateFilter)
+				modifiedAfter: dateBound(dateFilter),
+				signal: ctl.signal
 			});
+			if (seq !== runSeq) return; // superseded while awaiting
+			results = fresh;
 		} catch (e) {
+			// An aborted request is not an error — a newer run owns the UI.
+			if (seq !== runSeq || ctl.signal.aborted) return;
 			error = errorMessage(e);
 		} finally {
-			loading = false;
+			if (seq === runSeq) loading = false;
 		}
 	}