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).

server/index.js

@@ -393,6 +393,17 @@ function startBackgroundServices() {
   } catch (err) {
     console.warn("workflow poll failed to start:", err.message);
   }
+  // Codex lane stage detection. Codex emits no hooks at all, so its rollout
+  // journals on disk are the only signal a `codex` lane is working — without
+  // this poll such a lane's pipeline map never moves. `broadcastLane` (not the
+  // bare `broadcast(type, data)` above) is the single-lane push the hook route
+  // uses.
+  try {
+    const { broadcastLane } = require("./routes/lanes");
+    require("./lib/codex-ingest").startCodexPoll(broadcastLane);
+  } catch (err) {
+    console.warn("codex poll failed to start:", err.message);
+  }
   // Continuous discovery of sessions under ~/.claude/projects. The one-time
   // legacy backfill above runs only once (marker-gated), so a project added
   // later whose sessions never flow through hooks would otherwise stay invisible