[Bug]: orcad cannot create a terminal at all, and its agent chat renders nothing #17846

Operating system: Linux (Synology DSM, system-scope systemd service, paired iOS client)
Orca version: built from main at 94e758666 — between v1.4.191 and v1.4.192

Two startup steps --serve performs and orcad does not. On current main orcad
cannot create a terminal at all, and its agent chat cannot render.

1. orcad never calls runtime.syncWindowGraph(HEADLESS_RUNTIME_WINDOW_ID, ...).

--serve does, with a comment naming this exact hazard. orcad copies the
surrounding sequence and omits that one line, so graphStatus never leaves
'unavailable'. Two failures follow, and neither names the graph:

• session.tabs.createTerminal returns runtime_unavailable. The throw is
  assertGraphReady(), the first statement of
  runCreateMobileSessionTerminal — far above any PTY code, so a live daemon
  makes no difference.
• session.tabs.listAll does not fail, it hangs. No timeout, no error, no log.

2. orcad never starts the agent hook server.

Native chat reads the transcript path the hook reports
(providerSession.transcriptPath). The spawn path is already correct, but
buildPtyEnv() returns {} while the port is 0. Measured on the live agent
process: eight ORCA_* vars present, zero ORCA_AGENT_HOOK_* — so
claude-hook.sh returned at its first line on every invocation.

Repro:

1. Run orcad (not orca serve) against a scratch data root.
2. session.tabs.createTerminal → runtime_unavailable
3. session.tabs.listAll → no response, ever
4. The daemon log shows no create request was received, from any client.

The daemon is healthy throughout — it is simply never asked.