feat: API routes — speakers, rooms, search, RAG

Full implementations replacing stubs: speakers CRUD with utterance count,
rooms list + mute/unmute via pipeline, FTS5-based search, RAG /ask and
/summary endpoints. 15 route tests (8 new) all passing; 35 total.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/routes/test_search.py

@@ -0,0 +1,18 @@
+def test_search_returns_matches(api_client, seeded_db):
+    room = seeded_db.execute("SELECT id FROM rooms WHERE name='Kitchen'").fetchone()
+    seeded_db.execute(
+        "INSERT INTO utterances (room_id, transcript, match_status, start_time, end_time) VALUES (?,?,?,?,?)",
+        (room["id"], "the grocery list is ready", "unknown", "2026-01-01 10:00:00", "2026-01-01 10:00:03"),
+    )
+    seeded_db.commit()
+    resp = api_client.get("/api/search?q=grocery")
+    assert resp.status_code == 200
+    data = resp.json()
+    assert len(data) == 1
+    assert "grocery" in data[0]["transcript"]
+
+
+def test_search_no_results(api_client):
+    resp = api_client.get("/api/search?q=xyznotfound")
+    assert resp.status_code == 200
+    assert resp.json() == []