fix(cli,ui): connection recovery for stale Electron and daemon port changes

[Shadow-Azure]

Problem

When running cli-box start <command>, the CLI could hang indefinitely if:

• A stale Electron process was running but its renderer was disconnected
• The daemon restarted on a different port, breaking the renderer's WebSocket connection

Solution

CLI: Stale Electron Detection and Respawn

• Added kill_stale_electron() helper to detect and kill unresponsive Electron processes
• Modified cmd_start_daemon() to retry renderer connection after killing stale Electron
• Maximum 1 retry to prevent infinite loops

Electron: Port Change Detection on Reconnect

• Modified renderer WebSocket onclose handler to check daemon.json for port changes
• If daemon port changed (e.g., daemon restarted), renderer reconnects with new port

Test Plan

• Unit tests for kill_stale_electron() (no file, dead PID)
• All Rust tests pass (37 tests)
• All frontend tests pass (36 tests)
• TypeScript type check passes
• Manual test: fresh start works
• Manual test: stale Electron recovery works

[github-actions]

🔒 门禁检查结果

检查项	状态
Rust 格式化	✅ success
Rust Clippy	✅ success
Rust 测试 & 覆盖率	✅ success
前端测试 & 覆盖率	✅ success
Playwright E2E	✅ success
统一测试 (test.sh)	✅ success
安全检查	✅ success

Rust 测试覆盖率

指标	覆盖率
行覆盖率	69.8%
分支覆盖率	0.0%

模块	行覆盖率
crates.cli-box-core.src.daemon	███████████░░░░░░░░░ 56.2%
crates.cli-box-core.src.instance	███████████████████░ 99.1%
crates.cli-box-core.src.process	█████████████░░░░░░░ 65.7%
crates.cli-box-core.src.server	█████████████████░░░ 87.7%
crates.cli-box-core.src.capture	████████████████████ 100.0%
crates.cli-box-core.src.automation	███████████░░░░░░░░░ 58.8%
crates.cli-box-core.src.sandbox	███████████████████░ 98.8%
crates.cli-box-core.src	███████████░░░░░░░░░ 55.3%

详细报告见 Rust 覆盖率 artifact

前端测试覆盖率

指标	覆盖率
行覆盖率	████████████████░░░░ 82.3%
分支覆盖率	68.9%
函数覆盖率	80.0%
语句覆盖率	80.0%

文件	行覆盖率
src/tests/mocks/websocket.ts	██████████████████░░ 88.0%
src/tests/mocks/xterm.ts	████████████████████ 100.0%
src/renderer/api.ts	██████████████░░░░░░ 68.2%
src/renderer/tabState.ts	████████████████████ 100.0%

详细报告见前端覆盖率 artifact

✅ 所有检查通过，可以合入

点击 Squash and merge 合并此PR