[ChechiDev]

Summary

• Adds chrome.storage.onChanged.addListener so the extension reacts to config injected by the harness after browser lifecycle events have already fired
• Module-level CONFIG_CHANGE_KEYS Set covers all relevant keys (enable_sw_keepalive, work_server_url, work_server_token, allowed_clearance_domain, disable_task_polling, fatalStop)
• Reconciles keepalive alarm (swKeepalive) immediately after config injection — no longer requires a browser restart to take effect
• Does not call pollNextTask() or POST clearance — config reload only
• In-flight guard prevents concurrent reactions from multi-key storage writes
• try/catch/finally with console.error + persistStatus("err") on failure

Root cause

startAlarmIfNeeded() ran only at onInstalled/onStartup. At those lifecycle moments, the harness has not yet injected config, so enable_sw_keepalive is false — alarm never created. The sw_keepalive_confirmed gate (v0.47.7) confirmed this by blocking immediately after config injection.

Test plan

• 13 new TestStorageOnChanged tests: listener registered, async, area filter, loadConfig call, startAlarmIfNeeded call, ordering, error handling, no poll, no fetch, relevant keys including work_server_token and allowed_clearance_domain (membership in CONFIG_CHANGE_KEYS block, not whole-file presence), no raw value logging
• Full extension test suite (58 tests) passes
• Ruff + flake8 clean
• No real smoke executed

Closes #203