feat: Read My Mind phase 2, the predictor and the brain button

The feature as pitched in docs/readmymind-plan.md: pressing the header
brain button predicts the prompt you were about to type, from the case's
intent profile plus everything the session already knows.

Backend:
- readmymind-context.ts: pure budgeted context assembler (9 ranked
  sources: pending approval dialog, user goals, last assistant turn tail,
  recent prompts, tool activity, git workspace signals, away context,
  sibling sessions, rethink state; 30 KB budget, whole-section drop from
  the bottom of the ranking, trust tiers stated in the prompt)
- readmymind-collectors.ts: transcript tail reader (the live watcher
  keeps only a 500-char snippet) and git signal collection (execFile,
  2s timeout, skipped for remote-SSH cases)
- readmymind-predictor.ts: one-shot claude -p in a throwaway tmux
  session, opus by default (readMyMindModel setting), strict JSON
  contract with 1-3 suggestions (continue / verify / redirect), newline
  stripping, 90s timeout; mutable singleton so route tests can stub it
- POST /api/sessions/:id/readmymind: claude-mode only (400), one
  prediction in flight per session (409 CONFLICT), rethink body
  { steer, rejected }; ownership via findSessionOrFail

Frontend:
- readmymind-ui.js (loadorder 11.3): header brain button, marker-hidden
  until readMyMindEnabled is ON, desktop only (phone key is phase 3);
  modal with editable suggestion + rationale and Send / Insert /
  Rethink / Dismiss; suggestion text rendered via value/textContent only
  and nothing ever auto-sends
- App Settings -> Panels checkbox for readMyMindEnabled; en + zh-CN
  strings

Verified end to end against a live isolated instance: transcript
capture, a real opus prediction grounded in the stated goals, rethink
steering, the 409, and the browser modal incl. Insert leaving the text
unsubmitted on the composer. 41 new unit/route tests; full test:ci
sweep green (4680 tests).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

skills/codeman/SKILL.md

@@ -410,6 +410,22 @@ profile (`DELETE .../intent`) unless the user asks: it is their memory, not
 yours. Older servers 404 these routes; treat that as "feature absent", not an
 error.
 
+**Predict the user's next prompt.** The same profile feeds a one-shot
+predictor (claude-mode sessions only; takes 5-90 s and costs real tokens, so
+call it only when asked or when genuinely deciding what the user wants next):
+
+```bash
+"${CURL[@]}" -X POST -H 'Content-Type: application/json' -d '{}' \
+  "$API/api/v1/sessions/$SELF/readmymind" | jq '.data.suggestions'
+```
+
+Each suggestion is `{prompt, why, kind}` (`kind`: `continue` / `verify` /
+`redirect`). To re-run after a miss, pass `{"steer":"…","rejected":["…"]}` with
+the rejected prompt texts. A 409 means a prediction is already running for the
+session; a 400 means non-claude mode. ⚠️ Suggestions are **proposals for the
+user**: never send one into a session (yours or another's) unless the user
+explicitly asked you to act on it.
+
 Everything else (endpoint tables, per-mode signal table, error codes, capacity
 limits, Docker/remote caveats): [reference/endpoints.md](reference/endpoints.md).
 Fan-out orchestration and blocked-worker handling: