feat(lanes): prime and nudge codex lanes into declaring their own stage

A codex lane's declared stage has always depended entirely on the session
reading AGENTS.md and calling `ccam stage` on its own — no hook, no wrapper,
no enforcement. Two additions make that more reliable without touching the
declared-wins / inferred-never-done invariants:

- LaneConsolePane pre-fills a codex pane's opening prompt with a plain-text
  stage-declaration checklist built from the lane's own pipeline_nodes —
  the same up-front priming a Claude lane gets from its pre-filled
  /ccam:ship-feature-lane skill command, just as prose since Codex has no
  slash commands.
- server/lib/codex-nudge.js sweeps every 60s and types a one-line reminder
  into a lane's live tmux pane (tmux.sendText, a new literal-text primitive
  alongside sendCommand) when its fresh detected_stage has sat undeclared
  for over two minutes. It never writes stage/detected_stage itself — any
  resulting declaration is still the codex session's own real ccam stage
  call, just server-prompted instead of relying on memory alone.

server 1354/1354, client 449/449, tsc clean.

README.md

@@ -111,6 +111,11 @@ Sessions and Analytics. Its **stage detection** works anyway, from Codex's own
 rollout journals on disk (`$CODEX_HOME/sessions/**/rollout-*.jsonl`, polled every
 `DASHBOARD_CODEX_POLL_MS` ms, default 15000) — what a Codex lane cannot get for
 free is a *declared* stage, since only the session itself can call `ccam stage`.
+Two things help it get there: the run console pre-fills a codex pane's opening
+prompt with a stage-declaration checklist built from its own pipeline nodes,
+and a 60s sweep (`DASHBOARD_CODEX_NUDGE_MS`, `0` disables) types a one-line
+reminder into a lane's pane if its detected stage sits fresh and undeclared for
+more than two minutes.
 
 The declared stage comes from `ccam stage`. The inferred stage comes from tool
 events and expires after `DETECTION_TTL_MS` (default 5 minutes), so a lane can