feat(ml): lease announces detector config; agent builds proposers from it live (#134 step 2)

The GPU lease now carries the crop-proposer config from MLSettings in a per-job
'detectors' block (same pattern as embed_model_name). The agent's worker builds
its Proposers from the announced config via _effective_cfg (lease block overlaid
on env) + _proposers_for (rebuilds only when a config signature changes) — so an
operator's UI edit takes effect on the next lease with NO restart, and env is now
just the bootstrap fallback until the server announces. enabled-off maps to empty
weights (proposer skipped); dedupe_iou + max_regions also come from the effective
cfg. Test: lease announces the detectors block with the seeded default weights.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM

tests/test_api_gpu.py

@@ -105,6 +105,30 @@ async def test_lease_announces_embed_model_then_submit_embedding(client, db):
     assert img.siglip_embedding is not None and len(list(img.siglip_embedding)) == 1152
 
 
+@pytest.mark.asyncio
+async def test_lease_announces_detector_config(client, db):
+    # #134: the lease carries the crop-proposer config from MLSettings, so the
+    # agent builds its detectors from the DB/UI (no restart). Defaults are all-on
+    # with the pinned working weights.
+    img = await _img(db, "c" * 64)
+    await GpuJobService(db).enqueue(img.id, "embed")
+    await db.commit()
+    token = (await (await client.post("/api/gpu/token/rotate")).get_json())["token"]
+    hdr = {"Authorization": f"Bearer {token}"}
+
+    leased = await client.post(
+        "/api/gpu/jobs/lease", json={"agent_id": "a1", "batch_size": 5}, headers=hdr,
+    )
+    det = (await leased.get_json())["jobs"][0]["detectors"]
+    assert det["person"]["enabled"]
+    assert det["anatomy"]["enabled"]
+    assert det["panel"]["enabled"]
+    assert "yolov11m_aa22" in det["anatomy"]["weights"]      # booru_yolo default
+    assert det["panel"]["weights"].endswith("::best.pt")     # mosesb default
+    assert det["max_regions"] == 128
+    assert det["dedupe_iou"] == 0.85
+
+
 @pytest.mark.asyncio
 async def test_submit_with_stale_lease_is_409(client, db):
     img = await _img(db, "b" * 64)