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.

client/src/components/run/LaneConsolePane.tsx

@@ -145,19 +145,27 @@ export function LaneConsolePane({
   // templates never eats a typed requirement. Must be declared AFTER the
   // lane-switch effect: on a lane change that one clears both first.
   const lastPrefill = useRef("");
-  // Claude lanes only: the value is a Claude Code slash command, and Codex
-  // would take it as literal prose — a prompt it cannot execute is worse than
-  // an empty box (it also means the pipeline the skill drives never runs, so
-  // the lane declares no stage at all).
-  const pipelineSkill = laneTool === "codex" ? "" : currentLane?.pipeline_skill || "";
+  // Claude gets a slash command it can execute (`pipeline_skill`), which itself
+  // declares stage at every step. Codex has no slash commands — the same
+  // string would read as literal prose — so it gets the equivalent priming a
+  // different way: a plain-text checklist of this lane's own pipeline node ids,
+  // read directly off `pipeline_nodes` so it always matches the template in
+  // use. Without SOME opening nudge a codex lane's declared stage depends
+  // entirely on AGENTS.md being read on its own, which is easy to miss.
+  const promptPrefill =
+    laneTool === "codex"
+      ? currentLane?.pipeline_nodes?.length
+        ? `Declare progress as you go: run \`ccam stage <stage> --tool codex --evidence "..."\` immediately at each real transition through this pipeline — ${currentLane.pipeline_nodes.map((n) => n.id).join(" -> ")}. Then, your task:\n\n`
+        : ""
+      : currentLane?.pipeline_skill || "";
   useEffect(() => {
-    const next = pipelineSkill ? `${pipelineSkill} ` : "";
+    const next = promptPrefill && laneTool === "claude" ? `${promptPrefill} ` : promptPrefill;
     setPrompt((p) => (p === lastPrefill.current ? next : p));
     lastPrefill.current = next;
     // `laneId` is a dep too: switching between two lanes on the SAME template
-    // leaves `pipelineSkill` unchanged, and the switch effect just cleared the
+    // leaves `promptPrefill` unchanged, and the switch effect just cleared the
     // prompt — without it the new lane would open with an empty box.
-  }, [pipelineSkill, laneId]);
+  }, [promptPrefill, laneTool, laneId]);
 
   // The switch effect above only sees whatever `activeRuns` the page already
   // had loaded at that instant. Remounting this page (navigating away and