fix: recover terminal reattach after daemon idle

[Vaibhaav-Tiwari]

Summary

• add daemon identity to health/readiness probes so Electron can reject stale daemons from another checkout
• have Electron inspect and re-adopt a compatible existing daemon instead of staying on stale status
• refresh renderer daemon status while non-ready and gate terminal attach on daemon readiness

Closes #350

Tests

• cd backend; go test ./internal/httpd ./internal/cli
• cd frontend; pnpm.cmd run typecheck
• cd frontend; pnpm.cmd run test src/renderer/hooks/useTerminalSession.test.tsx src/renderer/hooks/useDaemonStatus.test.tsx

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