fix(pwa): restore the dashboard snapshot only for its own account

On a cold start the IndexedDB snapshot was restored before
/api/auth/me had answered, and the owner check was skipped while the
account was unknown. On a shared browser the previous account's
dashboard could be put into the next account's cache until the refetch
landed.

The restore now waits until the signed-in account is known and runs
again when it changes. A snapshot whose owner is not that account, or
that was written before any account was known, is discarded and wiped.

Because the restore now lands after the page has mounted, it fills
queries that have no data yet instead of skipping every query the cache
already knows; data the page holds is still never overwritten.

src/__tests__/baselines/version-stamp-comments.json

@@ -1,7 +1,7 @@
 {
   "$comment": "Comment lines that open with a release version, per file under src/. Maintained by src/__tests__/version-stamp-ratchet.test.ts.",
   "count": 2888,
-  "total": 9205,
+  "total": 9204,
   "entries": {
     "__tests__/account-payload-consumer-guard.test.ts": 2,
     "__tests__/acting-account-boundary-guard.test.ts": 7,
@@ -1277,7 +1277,7 @@
     "components/onboarding/welcome-screen.tsx": 1,
     "components/profile/__tests__/height-entry-surfaces.test.tsx": 1,
     "components/profile/height-field-control.tsx": 1,
-    "components/providers.tsx": 3,
+    "components/providers.tsx": 2,
     "components/records/about-me-note-manager.tsx": 3,
     "components/records/ai-profile-inclusion-manager.tsx": 1,
     "components/records/allergy-form.tsx": 1,