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_rooms.py

@@ -0,0 +1,14 @@
+def test_list_rooms(api_client, seeded_db):
+    resp = api_client.get("/api/rooms")
+    assert resp.status_code == 200
+    data = resp.json()
+    assert any(r["name"] == "Kitchen" for r in data)
+
+
+def test_mute_room_calls_pipeline(api_client, seeded_db, mocker):
+    mock_post = mocker.patch("app.api.routes.rooms.httpx.post")
+    mock_post.return_value.status_code = 200
+    room = seeded_db.execute("SELECT id FROM rooms WHERE name='Kitchen'").fetchone()
+    resp = api_client.post(f"/api/rooms/{room['id']}/mute")
+    assert resp.status_code == 200
+    mock_post.assert_called_once()