fix(lanes): auto-detect and report stage for codex lanes (issue 11)

A lane on the 16-node `ship-feature` template showed an untouched pipeline
map and never declared a stage. Four independent causes, fixed at their
shared choke points:

1. Codex emits no hooks, so `touchLaneFromHook` — the only caller of
   `stage-detect.detect()`, and correctly pinned to `claude` — could never
   see a `codex` lane. New `server/lib/codex-ingest.js` tails Codex's own
   rollout journals (`$CODEX_HOME/sessions/**/rollout-*.jsonl`), maps its
   tool calls onto the hook-shaped `{tool_name, tool_input}` the matcher
   already understands, and feeds the existing detect path plus an
   idle/running status mirror under the same guard hooks use. Polled every
   `DASHBOARD_CODEX_POLL_MS` ms (default 15000, `0` disables).
2. `resolveLaneArg` matched on cwd alone, so with a claude and a codex lane
   at one directory (the composite `idx_lanes_cwd_tool`) a `ccam stage`
   call could drive the sibling lane's card. It now resolves by
   `--lane` → `CCAM_LANE_ID` → `--tool`/harness marker → owning lane, and
   errors naming both candidates rather than picking one. Every pane the
   dashboard starts carries `CCAM_LANE_ID` (`tmux new-session -e`, or an
   assignment prefix when typing into a live shell pane).
3. `recordDetection`'s declared-wins veto had no exit: a lane left at the
   pipeline's last node rejected every detection for the rest of its life.
   A declaration on the LAST node no longer vetoes — the pipeline is over
   there, so a later detection is new work. Nothing else is relaxed, and
   detection still never writes `stage` nor renders `done`.
4. The run console pre-filled the pipeline's Claude slash command into
   codex panes, which Codex reads as prose — so the skill that would have
   called `ccam stage` never ran. Claude lanes only now.

A codex lane's *declared* stage still depends on the session calling
`ccam stage`; `AGENTS.md` is the only lever CCAM has, so it now says so.

Verified: server 1345/1345, client 441/441, and end-to-end against a real
codex lane row (detected_stage/detected_signal set, declared stage
untouched, no node rendered done).

README.md

@@ -107,7 +107,10 @@ Every lane also carries the CLI that drives it — `claude` (the default) or
 Codex lane's run panel offers Codex's own sandbox, approval and reasoning-effort
 choices, and resumes with `codex resume --last`. Codex emits none of this
 dashboard's hooks, so a Codex lane records its runs but stays absent from
-Sessions, Analytics and stage detection.
+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`.
 
 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