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/test_run_config_factory.py

@@ -107,7 +107,6 @@ def test_max_turns_default_is_300() -> None:
         tool_server_host_port=None,
         caido_host_port=None,
         agent_id="root",
-        agent_name="root",
         parent_id=None,
         tracer=None,
     )
@@ -124,7 +123,6 @@ def test_make_agent_context_full_shape() -> None:
         tool_server_host_port=48081,
         caido_host_port=48080,
         agent_id="agent-1",
-        agent_name="root",
         parent_id=None,
         tracer="not-a-real-tracer",
         is_whitebox=True,
@@ -154,7 +152,6 @@ def test_make_agent_context_is_whitebox_defaults_false() -> None:
         tool_server_host_port=None,
         caido_host_port=None,
         agent_id="r",
-        agent_name="root",
         parent_id=None,
         tracer=None,
     )