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_speakers.py

@@ -0,0 +1,26 @@
+def test_list_speakers_empty(api_client):
+    resp = api_client.get("/api/speakers")
+    assert resp.status_code == 200
+    assert resp.json() == []
+
+
+def test_create_speaker(api_client):
+    resp = api_client.post("/api/speakers", json={"name": "Alice"})
+    assert resp.status_code == 200
+    data = resp.json()
+    assert data["name"] == "Alice"
+    assert "id" in data
+
+
+def test_list_speakers_includes_utterance_count(api_client, seeded_db):
+    room = seeded_db.execute("SELECT id FROM rooms WHERE name='Kitchen'").fetchone()
+    speaker = seeded_db.execute("SELECT id FROM speakers WHERE name='Jeremy'").fetchone()
+    seeded_db.execute(
+        "INSERT INTO utterances (room_id, speaker_id, transcript, match_status, start_time, end_time) VALUES (?,?,?,?,?,?)",
+        (room["id"], speaker["id"], "hi", "known", "2026-01-01 10:00:00", "2026-01-01 10:00:01"),
+    )
+    seeded_db.commit()
+    resp = api_client.get("/api/speakers")
+    data = resp.json()
+    jeremy = next(s for s in data if s["name"] == "Jeremy")
+    assert jeremy["utterance_count"] == 1