feat: persistent session (no re-unlock on reload) + reconnect ACL after createRoom

Session persistence (web/src/session.ts): the unlocked wallet identity is kept
across reloads so an F5 no longer forces a password re-unlock. By default it lives
in sessionStorage (survives F5, cleared with the tab); with 'keep me signed in' it
lives in localStorage (survives closing the browser) bounded by a 30-day absolute
TTL and a 12-hour inactivity auto-lock. logout clears it; activity (send/createRoom)
refreshes the idle timer. No cookie is ever used — the private key never travels to
any server. WalletLogin gains the 'keep me signed in' checkbox; Recover/Join keep
the session by default (recovering/creating on a device implies it is yours).
App.tsx restores the session on mount before falling back to the unlock screen.

ACL reconnect: a room created while connected was not in the NATS per-subject ACL
grant (subjects are frozen at connect time), so its first messages silently did not
deliver until a re-login. WsNatsTransport gains reconnect(); BusClient.refresh()
calls it; busService.createRoom reconnects after creating so the new room is usable
immediately. Bumps uniweb to 0.4.0.

app.md

@@ -2,7 +2,7 @@
 name: uniweb
 lang: ts
 domain: infra
-version: 0.3.0
+version: 0.4.0
 description: "Cliente web browser-nativo del bus unibus: SPA de chat (React+Mantine) con wallet por usuario (BIP39) que habla DIRECTO al bus (nats.ws + control-plane HTTPS firmado), sin gateway. La clave privada nunca sale del navegador."
 tags: [messaging, web, frontend, e2e]
 uses_functions: []