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.

server/lib/tmux.js

@@ -9,6 +9,8 @@
  * The one place a command line is composed is `sendCommand`, which types into
  * an existing pane's shell: there the shell IS the consumer, so every argument
  * is POSIX single-quoted first and sent with `send-keys -l` (literal).
+ * `sendText` is the same primitive for the opposite case — a pane running an
+ * interactive chat program that reads stdin as a message, not a shell.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 
@@ -104,6 +106,20 @@ function sendCommand(name, argv, env) {
   execImpl(["send-keys", "-t", name, "Enter"]);
 }
 
+/**
+ * Type a literal line of plain text into an existing pane and press Enter —
+ * for a program that reads stdin as a message rather than a shell command
+ * (an interactive `claude`/`codex` chat pane), where `sendCommand`'s POSIX
+ * quoting and `KEY=value ` env prefix would show up as literal punctuation in
+ * the message instead of being interpreted. `text` must be single-line: `-l`
+ * sends it as one literal keystroke burst, so an embedded newline would submit
+ * only the first line and leave the rest sitting unsent in the input box.
+ */
+function sendText(name, text) {
+  execImpl(["send-keys", "-t", name, "-l", text]);
+  execImpl(["send-keys", "-t", name, "Enter"]);
+}
+
 /** Idempotent — a session that's already gone is not an error. */
 function killSession(name) {
   try {
@@ -142,6 +158,7 @@ module.exports = {
   enableMouse,
   paneCommand,
   sendCommand,
+  sendText,
   killSession,
   listSessions,
   isTmuxAvailable,