refactor: collapse dual stat buckets, prune unused params, kill dead helpers

Tracer:
- Collapse the ``live`` / ``completed`` LLM stat buckets into one
  flat dict. The ``completed`` bucket was only ever written by tests
  — production never moved stats across, and ``get_total_llm_stats``
  always summed both for display.
- Drop ``record_llm_usage(agent_id=...)``: argument was unused, and
  the per-call ``bucket=`` knob is gone with the buckets.

run_config_factory:
- Drop unused ``parallel_tool_calls``, ``tool_choice`` parameters
  from ``make_run_config`` — no caller ever overrode them.
- Drop ``agent_name`` from ``make_agent_context`` — set into the
  context dict but no consumer ever read it; the bus's ``names`` map
  is the source of truth.

Wire reasoning_effort through:
- ``Config.get("strix_reasoning_effort")`` is now actually plumbed
  to ``make_run_config`` from ``entry.py``. Previously the env var
  was advertised but never consumed.

Multi-agent graph tools:
- Replace six copies of
  ``inner = ctx.context if isinstance(ctx.context, dict) else {}``
  with a single ``_ctx(ctx)`` helper.

Todo tools:
- Lift the duplicated ``priority_order`` / ``status_order`` dicts
  to module-level ``_PRIORITY_RANK`` / ``_STATUS_RANK`` and replace
  both inline sort lambdas with ``_todo_sort_key``.

Notes tools:
- Delete ``append_note_content`` (and its test): docstring claimed
  it was for an "agents-graph wiki-update hook on agent_finish" that
  was never wired up. Pure dead public API.

Style:
- Drop the ``del ctx`` no-ops from notes / reporting / web_search
  tools. ``ARG001`` is already silenced project-wide for tool
  modules; the ``del`` was cargo-culted.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/telemetry/test_tracer.py

@@ -258,32 +258,26 @@ def test_events_with_agent_id_include_agent_name(
     assert chat_event["actor"]["agent_name"] == "Root Agent"
 
 
-def test_get_total_llm_stats_aggregates_live_and_completed(
+def test_get_total_llm_stats_aggregates_recordings(
     monkeypatch: pytest.MonkeyPatch, tmp_path: Path
 ) -> None:
     monkeypatch.chdir(tmp_path)
     tracer = Tracer("cost-rollup")
     set_global_tracer(tracer)
 
-    # Live agent (still running).
     tracer.record_llm_usage(
-        agent_id="root-agent",
         input_tokens=1_000,
         output_tokens=250,
         cached_tokens=100,
         cost=0.12345,
         requests=2,
-        bucket="live",
     )
-    # Completed agents (finalized — moved by on_agent_end hook).
     tracer.record_llm_usage(
-        agent_id="child-1",
         input_tokens=2_000,
         output_tokens=500,
         cached_tokens=400,
         cost=0.54321,
         requests=3,
-        bucket="completed",
     )
 
     stats = tracer.get_total_llm_stats()