Persist auto-lock activity across worker restarts

[HDauven]

Summary

• persist the auto-lock last-activity timestamp so a restarted MV3 background worker does not treat memory reset as infinite inactivity
• initialize missing activity for an already-unlocked wallet instead of locking on the first alarm after restart
• refresh persisted activity on unlock, user-controlled extension UI heartbeats, auto-lock setting changes, successful post-approval dApp action methods, and real dApp network switches that actually change node URL
• do not refresh activity for passive connected dApp polling such as profile reads, public balance reads, chain ID reads, shielded-address reads, or no-op network switches
• clear persisted activity on manual or automatic lock
• document the session-storage-backed auto-lock activity behavior

Provider event contract

• dusk_profiles returns [] when an origin is authorized but the wallet is locked
• dusk.isAuthorized === true plus profiles.length === 0 is the connected-but-locked state
• manual lock and auto-lock call the profile broadcaster, and connected dApp ports receive profilesChanged([]) while remaining authorized
• connected-but-locked dApps can call dusk_requestProfiles to enter the unlock/reconnect approval path

Root cause

lastActivityTimestamp only lived in service worker memory. When the worker slept or restarted, it reset to 0; the next chrome.alarms auto-lock check computed a huge elapsed time and locked immediately. Since the alarm runs about once per minute, this looked like a 1-minute lock even with a 5-minute setting.

Review follow-up

Validated and fixed the P1 finding that connected dApps could keep the wallet unlocked by polling successful no-approval RPCs. The activity refresh allowlist now excludes passive/read/no-op dApp methods, and regression tests cover dusk_profiles, dusk_getPublicBalance, dusk_chainId, and no-op dusk_switchNetwork.

Validation

• npm ci
• npm run test:run -- src/background/autoLock.test.js src/background/dappEvents.test.js src/background/rpc.test.js src/integration/providerDiscovery.test.js src/background/lifecycle.conformance.test.js src/background/txLifecycle.flow.test.js
• npm run test:run
• npm run build:chrome
• npm run build:firefox
• git diff --check