Add job run logs, OpenRouter model picker, and discipline grouping.

- Job logs: each job's stdout/stderr is teed into outputs/<id>/job.log
  (survives restarts) and served at GET /jobs/{id}/log as text/plain, so
  full run logs can be shared for debugging and refinement.
- Model picker: GET /models proxies OpenRouter's public model list with
  per-1M-token pricing (1h cache, 502 on failure); the UI shows a model
  dropdown with costs when OpenRouter compute is selected, and the pick
  overrides vision+text models for that job (Classic and Agent modes).
- Conflicts in the report view are grouped by discipline pair
  (collapsible sections, severity-ordered within groups) instead of one
  flat severity-only list.

tests/test_llm_model_override.py

@@ -0,0 +1,26 @@
+from backend import config
+from backend.llm import _resolve_backend, set_model_override
+
+
+def test_override_wins_for_vision_and_text():
+    set_model_override("openai/gpt-4o")
+    try:
+        assert _resolve_backend(has_images=True, model_override=None)["model"] == "openai/gpt-4o"
+        assert _resolve_backend(has_images=False, model_override=None)["model"] == "openai/gpt-4o"
+    finally:
+        set_model_override(None)
+
+
+def test_override_beats_per_call_model_arg():
+    set_model_override("openai/gpt-4o")
+    try:
+        # Agents pass their AGENT_*_MODEL per call; the user's job pick wins.
+        assert _resolve_backend(has_images=False, model_override="other/model")["model"] == "openai/gpt-4o"
+    finally:
+        set_model_override(None)
+
+
+def test_no_override_keeps_defaults():
+    set_model_override(None)
+    assert _resolve_backend(has_images=True, model_override=None)["model"] == config.MODEL
+    assert _resolve_backend(has_images=False, model_override=None)["model"] == config.TEXT_MODEL