feat(browser): add configurable daemon port for multi-Chrome-profile support

[chenbojian]

Summary

Closes #1089

When multiple Chrome profiles each have the OpenCLI extension installed, they all connect to localhost:19825, and the daemon's single extensionWs global means the last profile to connect "wins". This PR adds per-profile daemon port configuration so each profile can target a separate daemon process.

Changes

• extension/manifest.json: Add storage permission for chrome.storage.local
• extension/src/background.ts: Read daemon port from chrome.storage.local on startup (default 19825); listen for storage.onChanged to reconnect when port is updated; include port in popup status response
• extension/popup.html + popup.js: Add daemon port input field with save button; show current port in status display
• extension/src/background.test.ts: Add chrome.storage mock to createChromeMock()

No changes needed in

• src/daemon.ts — already supports OPENCLI_DAEMON_PORT env var
• src/browser/daemon-client.ts — already supports OPENCLI_DAEMON_PORT env var
• extension/src/protocol.ts — default constants still used as fallback

Test plan

• Load extension with no storage config — should connect to localhost:19825 as before (zero-config default unchanged)
• Open popup, set port to 19826, save — extension should disconnect and reconnect to new port
• Start two daemons on different ports, configure two Chrome profiles with different ports — both connect independently
• Enter invalid port (e.g., 999, 70000) — validation prevents save
• All existing tests pass (npx vitest run — 22 passed, 1 pre-existing skip)