feat: time awareness — Lyra perceives 'now' and how long it's been

She had no clock: current date/time and the gap since Brian last spoke were
invisible between turns, and reflection was timeless. Now:
- lyra/clock.py: wall-clock stamp + coarse human gaps ("3 days")
- chat: inject a 'now' note (date/time + gap since last turn) after her
  self-state — when she is, before the world
- reflect(): feed current time + silence gap into reflection, neutrally —
  prompt invites her to weigh elapsed time "to whatever degree it genuinely
  affects you" (no prescribed feeling; whether silence means anything is left
  to emerge)
- memory.last_exchange_at(): timestamp of the most recent exchange

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 config, llm, logbus, memory, persona, self_state, summary
+from lyra import clock, config, llm, logbus, memory, persona, self_state, summary
 from lyra.llm import Backend, Message
 
 RECALL_K = 3  # raw cross-session "sharp detail" hits
@@ -30,6 +30,21 @@ def _detail_note(exchanges: list[memory.Exchange]) -> Message:
     return {"role": "system", "content": body}
 
 
+def _now_note() -> Message:
+    """Current wall-clock time + how long since Brian last said anything.
+
+    Stated as plain fact — she has no clock otherwise, so without this 'now' and
+    the gap since the last turn are invisible to her.
+    """
+    line = f"The current date and time is {clock.stamp()}."
+    gap = clock.humanize_gap(memory.last_exchange_at())
+    line += (
+        f" It has been {gap} since Brian last spoke with you."
+        if gap else " This is the first thing Brian has ever said to you."
+    )
+    return {"role": "system", "content": line}
+
+
 def _render(messages: list[Message]) -> str:
     """Human-readable dump of the exact prompt, for the live-log inspector."""
     return "\n\n".join(f"[{m['role']}]\n{m['content']}" for m in messages)
@@ -43,6 +58,9 @@ def build_messages(session_id: str, user_msg: str) -> list[Message]:
     # right after the persona — her sense of self before her model of the world.
     messages.append({"role": "system", "content": self_state.render_for_context(self_state.load())})
 
+    # When she is: current time + the gap since Brian last spoke (she has no clock).
+    messages.append(_now_note())
+
     # 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()