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/cli.py

@@ -1,5 +1,6 @@
 import atexit
 import contextlib
+import logging
 import os
 import signal
 import sys
@@ -24,6 +25,9 @@ from .utils import (
 )
 
 
+logger = logging.getLogger(__name__)
+
+
 def _resolve_sandbox_image() -> str:
     image = load_settings().runtime.image
     if not image:
@@ -182,6 +186,12 @@ async def run_cli(args: Any) -> None:  # noqa: PLR0915
             update_thread.start()
 
             try:
+                logger.info(
+                    "CLI launching scan: run_name=%s targets=%d interactive=%s",
+                    args.run_name,
+                    len(scan_config.get("targets") or []),
+                    bool(getattr(args, "interactive", False)),
+                )
                 await run_strix_scan(
                     scan_config=scan_config,
                     scan_id=args.run_name,