feat(logging): per-scan `{run_dir}/strix.log` with scan/agent context tagging

Every scan now writes a complete log file at ``{run_dir}/strix.log``
captured from the moment ``run_dir`` is resolved through teardown.
Stdlib ``logging`` only — no parallel framework.

New ``strix/telemetry/logging.py``:
  * ``setup_scan_logging(run_dir, debug=)`` attaches a ``FileHandler``
    (DEBUG, all ``strix.*``) plus a ``StreamHandler`` (ERROR by
    default; DEBUG via ``STRIX_DEBUG=1``).
  * ``ContextVar``-backed ``scan_id`` and ``agent_id`` injected by a
    ``Filter`` so every line is auto-tagged across asyncio tasks
    without callers passing them explicitly.
  * Third-party noise (``httpx``, ``litellm``, ``openai``,
    ``anthropic``, ``urllib3``, ``httpcore``) capped at WARNING.
  * Returns a teardown handle for ``finally`` cleanup.

Wiring:
  * ``orchestration/scan.py`` calls ``setup_scan_logging`` once per
    scan after ``run_dir`` resolves; sets scan_id; tears down in
    ``finally``. Adds INFO logs for sandbox bring-up + scan
    start/end.
  * ``orchestration/hooks.py`` sets/clears ``agent_id`` ContextVar in
    ``on_agent_start`` / ``on_agent_end`` and emits INFO for agent
    lifecycle, DEBUG for every tool start/end and LLM call.
  * ``interface/main.py`` drops the ``setLevel(ERROR)`` silencer.

Coverage expanded across ~20 files (orchestration, agents, runtime,
llm, tools, interface, config, skills) with INFO for lifecycle and
DEBUG for verbose detail. Per the system instructions in
``logger.warning(f"…{e}")`` were converted to module logger calls.

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

strix/interface/main.py

@@ -5,7 +5,6 @@ Strix Agent Interface
 
 import argparse
 import asyncio
-import logging
 import shutil
 import sys
 from pathlib import Path
@@ -43,7 +42,11 @@ from strix.telemetry.tracer import get_global_tracer
 HOST_GATEWAY_HOSTNAME = "host.docker.internal"
 
 
-logging.getLogger().setLevel(logging.ERROR)
+# Per-scan logging is set up by ``setup_scan_logging`` from inside
+# ``orchestration.scan.run_strix_scan`` once the scan ``run_dir`` is
+# known — that's where ``strix.*`` levels and handlers are owned. Pre-scan
+# work (``main()``, env validation, image pull) emits at WARNING+ to
+# stderr via the SDK / stdlib defaults.
 
 
 def validate_environment() -> None: