feat: live chat deliberation — think privately before answering (less 'meh')

The chat had no thinking in it: respond() was a single gpt-4o call in default-
assistant voice (numbered lists, 'would you like to...', vague). All the cognition
work was background-only. This brings a thought step into the conversation.

- chat: before answering a substantive turn (trivial 'ok/lol' skipped), a private
  _deliberate() pass — "what do you ACTUALLY think, your real take, the substance,
  no pleasantries" — drawing on her in-context threads/journal. The thinking is then
  injected as the LAST system note with voice enforcement (answer from this; no
  numbered list / how-to outline unless asked; no 'would you like to' closer), so it
  beats gpt-4o's boilerplate at the most influential position. Logged to /logs.
- Wired into respond() + respond_stream(). Config CHAT_DELIBERATE (default on) to
  disable if the extra call's latency annoys.
- persona: "talk, don't outline" — prose over listicles, the first concrete move
  over a survey of options.
- test_chat.py (gating + note composition + disabled). Suite 84, ruff clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.env.example

@@ -48,3 +48,4 @@ INTROSPECTION_MODEL=
 PING_AUTO_SALIENCE=0.8   # a thought this salient auto-pings even without an explicit reach-out
 PING_COOLDOWN_MIN=60     # min minutes between AUTO pings (explicit reach-outs bypass)
 DIGEST_HOUR=18           # local hour to send her daily "what I've been thinking" digest
+CHAT_DELIBERATE=true   # think privately before answering substantive chat turns (false = faster, shallower)