feat: rotation progress spinner + quick-unlock re-wrap on master-pw change

- doChangeMasterPassword shows the busy overlay while it re-encrypts the
  vault: "Re-encrypting vault…" → "Re-encrypting entries… N/total" →
  "Re-encrypting attachments… N/total", cleared in finally. A rotation on
  a big vault took tens of seconds with no feedback before.
- Quick-unlock now SURVIVES a master-pw change instead of being wiped.
  The blob stores the raw key (DPAPI-wrapped, no user secret), so it's
  re-wrapped in place with the new key/salt/iters/algo (state already
  holds the new values at that point). Cold-start then re-logs in with a
  verifier derived from the new key. Falls back to clearing if the
  re-wrap throws, so a stale old-key blob is never left behind.
- PIN blob still cleared (wrapped by PBKDF2(pin) — can't re-wrap without
  the PIN). A setTimeout(0) separates the quickunlock/store and pin/clear
  navigations so the back-to-back window.location.href assignments don't
  coalesce and drop the re-wrap.
- Fixed a `failed` counter declaration accidentally dropped from the
  attachment re-encryption loop while adding progress (ReferenceError at
  runtime; node --check wouldn't catch it).
- CLAUDE.md updated for the re-wrap vs clear distinction.

Rebuild: BuildAssets + F9 (JS only this commit; F9 to re-embed).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CLAUDE.md

@@ -581,9 +581,15 @@ bypasses the PIN check (the device is already trusted).
 Sensitive actions (`askReauth` paths: export, change master pw,
 recovery code, etc.) ALWAYS require master pw — PIN never substitutes.
 
-Master pw rotation clears the PIN blob (same reason as Quick Unlock :
-stored wrapped key + server verifier drift). User re-sets PIN from
-Settings after rotation.
+Master pw rotation **clears the PIN blob** (stored wrapped key + server
+verifier drift). Unlike Quick Unlock — which stores the raw key directly
+(DPAPI-wrapped, no user secret) and is therefore **re-wrapped in place**
+with the new key/salt/iters/algo during rotation so it survives — the PIN
+blob is wrapped by `PBKDF2(pin)` and can't be re-wrapped without the PIN,
+so it's wiped and the user re-sets it from Settings. `doChangeMasterPassword`
+does the two via `window.location.href` (quickunlock/store then pin/clear)
+with a `setTimeout(0)` between them so the back-to-back navigations don't
+coalesce and drop the re-wrap.
 
 ## Quick Unlock