feat: runtime feature flags, upload/download, RAW decoding

Adds Redis-backed feature flags for vision stages with admin UI toggles
and manual backfill trigger, photo upload and download routers with
frontend upload modal, and rawpy-based RAW decoding with JPEG fallback
for misnamed DNGs. Fixes pgvector serialization, is_trashed filter, and
naive-datetime bind in incremental duplicate regrouping; bumps Celery
time limits on regroup tasks beyond the 5-minute default.

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

frontend/src/hooks/useFeaturesQuery.ts

@@ -0,0 +1,39 @@
+import { useQuery, useQueryClient } from '@tanstack/react-query'
+import { features, type FeaturesMap } from '../services/api'
+
+export const FEATURES_QUERY_KEY = ['features'] as const
+
+/** Read the effective feature-flag state (admin override or YAML
+ *  default). Powers conditional rendering of pipeline-dependent UI —
+ *  People view, Tags view, OCR snippets, etc. */
+export function useFeaturesQuery() {
+  return useQuery<FeaturesMap>({
+    queryKey: FEATURES_QUERY_KEY,
+    queryFn: features.list,
+    // Re-read every minute so admin toggles reflect without a page
+    // reload. The admin tab also invalidates this key on write so the
+    // refresh can be immediate for the admin who just flipped it.
+    staleTime: 60_000,
+    refetchInterval: 60_000,
+  })
+}
+
+export function useIsFeatureEnabled(
+  name:
+    | 'vision.enabled'
+    | 'vision.ocr.enabled'
+    | 'vision.detector.enabled'
+    | 'vision.faces.enabled'
+    | 'vision.classifier.enabled',
+): boolean {
+  const { data } = useFeaturesQuery()
+  // Default to enabled while loading so we don't flash "feature off"
+  // during a first-paint fetch. The backend is the source of truth;
+  // any gated UI that slipped through just returns empty data anyway.
+  if (!data) return true
+  return !!data[name]
+}
+
+export function invalidateFeaturesQuery(queryClient: ReturnType<typeof useQueryClient>) {
+  queryClient.invalidateQueries({ queryKey: FEATURES_QUERY_KEY })
+}