feat: thought loop — Lyra's threaded, surfaceable train of thought

Built from her own 6-19 idea: a continuing train of thought she keeps across
days, organized into threads she returns to, that she can bring TO Brian and
that his feedback advances or closes. Where the dream cycle's reflect() gives
isolated, overwriting reflections, the thought loop adds continuity (threads),
surfacing (#6 — she leads with a thought when Brian returns after a gap), and a
feedback loop (his reply folds in next pass).

- lyra/thoughts.py: thought_threads + thoughts tables; think() with
  new/continue/respond modes; salience-gated maybe_surface(); record_response()
  feedback; lazy-schema _c() mirroring poker.
- dream.py: curiosity stage advances the loop after reflecting (error-isolated).
- chat.py: build_messages surfaces the top thread after a >=90min gap, once.
- web: /thoughts feed (page + data + respond + status routes), thoughts.html,
  nav 💭 entry. lyra-think entry point. Every thought also lands in her journal.
- clock.gap_seconds(); tests/test_thoughts.py (8 tests). Full suite 58 passing.

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

lyra/chat.py

@@ -10,7 +10,7 @@ After replying, the session is compacted if enough new turns have accumulated.
 """
 from __future__ import annotations
 
-from lyra import clock, config, llm, logbus, memory, modes, persona, self_state, summary
+from lyra import clock, config, llm, logbus, memory, modes, persona, self_state, summary, thoughts
 from lyra import tools as toolkit
 from lyra.llm import Backend, Message
 
@@ -105,6 +105,14 @@ def build_messages(session_id: str, user_msg: str,
     # When she is: current time + the gap since Brian last spoke (she has no clock).
     messages.append(_now_note())
 
+    # Thought loop: if Brian's been away and one of her own threads has built past
+    # the surface bar, let her lead with it (once). This is her #6 — bringing what
+    # she thought about while alone *to* him. Runs before the world-model tiers so
+    # it's framed as her interiority, like the self-state.
+    surfaced = thoughts.maybe_surface(memory.last_exchange_at())
+    if surfaced:
+        messages.append({"role": "system", "content": surfaced})
+
     # Semantic memory: the distilled profile (who Brian is) — answers identity
     # questions that raw recall can't. Always in context when it exists.
     profile = memory.get_profile()