feat: custom message types for system turns — wake and verdict messages

The custom-message scheme (user-decided 2026-09-12): system-authored
user-role messages are NOT human messages — they carry marker data parts
only, the adapter owns their model-facing wording, and the UI renders
them under control. Nothing fake is ever persisted as human speech.

The inventory (all migrated):
- probe→teacher handoff wake: was a text-bearing user message rendering
  as a fake user bubble; now data-probe-handoff marker-only — the
  adapter flattens it to HANDOFF_TEXT (core/contracts/chat.ts), the UI
  renders a quiet 'Preparing your plan…' system line.
- plan accept/decline: was boilerplate text ('The plan is accepted…',
  'I'd like the plan revised…') masquerading as learner speech — the
  decline wasn't even marked; now data-verdict {accepted, at} on its own
  message, adapter flattens to verdictText(), UI renders the quiet
  verdict marker ('✓ Plan accepted' / '↻ Plan revision requested').
  sendVerdict sends TWO REAL MESSAGES when the learner typed a note
  (the note as a genuine user message, then the verdict) in ONE turn
  via setMessages + sendMessage() — no 409 dance, no double teacher turn.
- sub-agent steers: the abort steer gains its data-subagent-aborted
  marker part; the UI keys steer rendering off PARTS (artifact/aborted),
  not metadata — metadata stays as pump mechanics only.
- record-adapter: systemTextOf() flattens marker-only messages; steers
  keep their text (payload — briefs are content, not boilerplate).

phases.ts: plan→teach advances on data-verdict{accepted:true} only;
learner text alone can never sanction teaching (pinned). data-plan-
accepted retired, no back-compat (user-decided: wiped-data doctrine).

Pinned: record-adapter.test.ts (verdict/handoff flattening, note+verdict
order, steer payload kept, UI-only parts skipped), phases.test.ts
(verdict marker semantics, out-of-order, text-never-fakes), jobs.test.ts
(abort marker part), demos.test.tsx (badge renders off the part, not
metadata).

Live GLM smoke (disposable driver, deleted): probe→conclude→wake→plan→
decline-with-note (revised, still plan)→accept-with-note (teach) — ALL
CHECKS PASS, including marker-only handoff/verdict on the wire and zero
fake human speech in the transcript.

Gates: tsc, lint, build, 335/335.

src/core/phases.ts

@@ -6,9 +6,10 @@
  *   probe  — until the first message containing a `tool-probe_done` part
  *            (the prober concludes; the assessment rides the tool part)
  *   plan   — probe concluded, until the learner ACCEPTS the presented
- *            plan (a `data-plan-accepted` part on the accept button's
- *            user message — the explicit verdict gate; plan_init itself
- *            is only the PRESENTATION and moves no phase)
+ *            plan (a `data-verdict` part with accepted:true on the verdict
+ *            button's own user message — the explicit verdict gate;
+ *            plan_init itself is only the PRESENTATION and moves no
+ *            phase; a declined verdict stays in plan)
  *   teach  — teaching is sanctioned
  *
  * The former derived-occupancy seam (phase-of-tree via `currentNodeId`)
@@ -49,14 +50,18 @@ function advance(
 	if (!parts) return phase;
 	for (const part of parts) {
 		// STRICTLY SEQUENTIAL: probe → plan only via a concluded probe_done,
-		// plan → teach only via the learner's plan acceptance
-		// (data-plan-accepted). A marker out of order advances nothing — the
+		// plan → teach only via the learner's plan acceptance (data-verdict
+		// with accepted:true). A marker out of order advances nothing — the
 		// chain never skips. plan_init PRESENTS the map; only the verdict
-		// (the accept button's marker part) sanctions teaching.
+		// sanctions teaching (a decline stays in plan).
 		if (phase === "probe" && part.type === "tool-probe_done" && part.state === "output-available") {
 			phase = "plan";
 		}
-		if (phase === "plan" && part.type === "data-plan-accepted") {
+		if (
+			phase === "plan" &&
+			part.type === "data-verdict" &&
+			(part as { data?: { accepted?: unknown } }).data?.accepted === true
+		) {
 			phase = "teach";
 		}
 	}