feat: behind-the-scenes 👍/👎 rating system (fine-tune data collection)

Brian can rate Lyra's outputs as he uses her; each rating is stored as a
(context, content, rating) triple — the shape a future fine-tune / preference
dataset wants, collected passively during real use.

- memory: ratings table + add_rating (upsert: one row per item, re-rating
  replaces), list_ratings, rating_counts
- server: POST /rate, GET /ratings/counts, GET /ratings/export (JSONL download)
- chat UI: subtle 👍/👎 on each assistant reply, captures the prompting message
  as context
- journal/reflection UI: 👍/👎 on each thought
- tests: counts + upsert-replace behavior

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

lyra/web/server.py

@@ -142,6 +142,32 @@ def create_app() -> FastAPI:
     async def journal_data(limit: int = 300) -> dict:
         return {"entries": memory.list_journal(limit=limit)}
 
+    @app.post("/rate")
+    async def rate(request: Request) -> dict:
+        """Record Brian's 👍/👎 on a Lyra output (chat reply, reflection, journal)."""
+        b = await request.json()
+        rating = int(b.get("rating", 0))
+        content = (b.get("content") or "").strip()
+        if not content or rating == 0:
+            return {"ok": False}
+        memory.add_rating(
+            kind=b.get("kind") or "chat", rating=rating, content=content,
+            context=(b.get("context") or None), ref=b.get("ref"), note=b.get("note"),
+        )
+        logbus.log("info", "rating", kind=b.get("kind"), rating=1 if rating >= 0 else -1)
+        return {"ok": True, "counts": memory.rating_counts()}
+
+    @app.get("/ratings/counts")
+    async def ratings_counts() -> dict:
+        return memory.rating_counts()
+
+    @app.get("/ratings/export")
+    async def ratings_export() -> Response:
+        """All ratings as JSONL — the seed for a future fine-tune / preference set."""
+        lines = "\n".join(json.dumps(r) for r in memory.list_ratings())
+        return Response(content=lines + ("\n" if lines else ""), media_type="application/x-ndjson",
+                        headers={"Content-Disposition": 'attachment; filename="lyra_ratings.jsonl"'})
+
     @app.get("/hand/{hand_id}")
     async def hand_page(hand_id: int) -> FileResponse:
         """Replayable hand-history viewer."""