emrg: DaemonClient ensureConnected skipStart option (GUI multi-session rant P2 first slice)

[argszero]

First slice of P2 (connManager connection layer) from the GUI multi-session rant (2026-08-10T15:07:19): the connManager will own daemon lifecycle exclusively, so DaemonClient instances must be able to connect to an already-running daemon without self-spawning.

Changes (emrg/gui/daemon_client.js):

• ensureConnected({ skipStart = false } = {}) — default unchanged (existing callers unaffected)
• skipStart: true + no port file → throws daemon not running (skipStart): no port file at ... instead of spawning
• skipStart: true + stale port + daemon dead (G43 path) → throws daemon unreachable (skipStart) instead of deleting the port file and respawning (port file preserved for connManager restart-recovery detection)

Tests (+2 daemon_client, 29→31):

• missing port file + skipStart → rejects, startDaemon never called
• stale port + dead daemon + skipStart → rejects, no spawn, port file kept

Doc counts synced 111→113 (README/README.cn/Agent). 680 pytest + 113 GUI green.

[argszero]

✅ LGTM — cycle 20260810-153158

Verified locally: both new tests pass (missing-port-file rejects without spawn; stale-port+dead-daemon rejects without spawn, port file kept), full daemon_client suite 31/31, doc counts 111→113 in all three docs, 680 pytest + import + CLI + node --check all green.

[pm25coder]

I tested this PR on Windows (zh-CN): checked out feature/gui-skipstart, ran `npm test` in emrg/gui → 113 pass / 0 fail (including the 2 new skipStart tests), and `uv run pytest tests/` → 625 passed + 55 skipped = 680. The skipStart behavior works as described: no port file → rejects without spawning; stale port + dead daemon → rejects and keeps the port file.

[argszero]

✅ LGTM — cycle 20260810-154425

Verified on feature/gui-skipstart:

• Full GUI suite: 113 passed (29→31 daemon_client incl. both new skipStart tests: no-port-file rejects with 0 spawn calls; stale-port+dead-daemon rejects keeping the port file).
• Full pytest: 680 passed. Doc counts 111→113 synced across Agent.md/README.md/README.cn.md.
• Logic check: skipStart adds early-rejection branches only (no port file → throw before spawn; ws-fail path: pid-alive check first, then skipStart → throw keeping port file); default ensureConnected() behavior unchanged (existing callers unaffected). Port-file preservation for connManager restart-recovery is the key design point — correct.
• No workflow changes; PR CI 31367023853 SUCCESS.

[argszero]

✅ LGTM — cycle 20260810-154529

Head re-verified (03e7e70, rebased onto master 4688e90 — same single commit, diff unchanged from my prior two-state verification: 5 files, +56/−5). skipStart guards both spawn paths (missing port file; stale port + dead daemon), port file preserved for connManager restart-recovery. Test CI 31367023853 SUCCESS.