feat(mods): let a Mod submit a prompt of its own in headless runs (#16302)

* feat(mods): let a Mod submit a prompt of its own in headless runs

$.prompt.submit({ text, asUser? }) raises prompt.submit through every hook
but the caller's, with the Mod as its origin, and queues what arrives
beneath them. The headless run takes it once idle and runs it as a turn of
its own: UserPromptSubmit hears it, turn.start and turn.complete fire, and
the transcript records it with the provenance mod_prompt and the Mod's
name. Unless the Mod passes asUser, the model reads the text inside a block
that names the Mod and says the person did not type it.

The call resolves once its prompt is queued, as next(e) does for a typed
prompt. The Mods' prompts start at most 8 turns before the person sends a
prompt. The terminals do not run these prompts yet: there the method is not
listed and a call resolves to a drop.

* fix(mods): queue a Mod's prompt once, outside its caller's lifetime

- Run the hooks a `$.prompt.submit` raises outside the calling hook, so a
  call the hook does not await still queues after the hook returns.
- Queue what last arrived beneath the hooks once they have all answered,
  so a hook that calls `next(e)` twice queues one prompt.
- Drop an empty or whitespace-only text, from the call or from a hook.
- Discard Mod prompts that have not started when a headless run ends, so a
  stream-json session does not run them on the client's next message.
- Escape every `<` and `>` in the framed text.
- Recall memory for the Mod's text rather than the frame, keep a Mod's
  prompt out of the session title (in its turn's place) and out of the
  commit attribution's prompt count.

* fix(mods): keep the title, SDK output and turn count right for Mod prompts

- Mark a Mod's prompt as `null` in the title projection, not `''`, so it
  no longer switches a session whose prompts recorded no display text to
  an empty projection, which stopped auto-title and `/rename --auto`.
- Tell a stream-json client of a Mod's prompt: its text as a user message,
  then a `mod_prompt` system message naming the Mod, before the turn runs.
- Reset the Mods' turn count for the person's slash commands too.
- End a Mod turn that a duplicate provider call stops as an error on the
  shared loop, as on the legacy loop and for the main turn.
- Refuse a prompt submitted while /clear or /resume ends the session, and
  start the new session with nothing queued and the count at 0.

* fix(mods): keep charging a hook while the other Mods hear its submit

A $.prompt.submit call outlives its caller, yet it lent the caller's
budget for the whole submit chain, so a hook that did not await it ran
unbudgeted until the other Mods' prompt.submit hooks answered. It now
runs as the void notices do, charging the caller as it goes.

The frame also no longer says the Mod sent its prompt while the session
was idle: most are sent mid-turn and wait for the session to be idle.

* fix(mods): run a Mod command's submitted prompt and keep it out of the title

A Mod command in a headless run always answers with a message, and that
branch returned before the drain, so a prompt the command submitted with
$.prompt.submit was discarded while the call had resolved as queued. The
reply is now shown without a turn of its own and the run goes on to the
drain, ending with one result.

A session whose prompts recorded no display text drew its title from the
conversation, which held the Mod's framed prompt. The recorder now keeps
the text the model read for each Mod prompt, and the conversation-based
title leaves those messages out.

* fix(mods): keep a Mod's prompt within its payload and its command's reply in view

- Drop a submitted prompt past half a Mod payload, from the call or a
  hook's rewrite, before it is queued, so a queued prompt is never
  reported as failed; an input too large for the bridge now rejects.
- Print a Mod command's reply in text output, and give the worktree notice
  the command would have carried to the first request the run sends.
- Leave an `asUser` Mod prompt out of the title keys, which matched a
  prompt the person typed alike, and keep the keys least recently used.
- Make Goal evidence leave a Mod's prompt out explicitly.
- Pin the documented turn limit and the tool-result guard in tests, and
  add a built-CLI test of `$.prompt.submit` against the fake server.
- Docs: six steps, the non-goal narrowed, the hook docs and the budget
  paragraph naming Mod prompts.

* test(mods): run the $.prompt.submit integration test in the no-AK job

scripts/tests/no-ak-integration-ci.test.js

@@ -229,6 +229,7 @@ describe('no-AK integration CI wiring', () => {
       './cli/list_directory.test.ts',
       './cli/tool-hook-context.test.ts',
       './cli/tool-hook-updated-input.test.ts',
+      './cli/mods-prompt-submit.test.ts',
       './cli/qwen-serve-routes.test.ts',
       './cli/qwen-serve-session-cd.test.ts',
       './cli/qwen-serve-streaming.test.ts',