refactor(monitoring): N2 - tach monitoring_tab.py, CanonicalAuditLogger, MonitoringQueryService, go circular import, sandbox matrix

- ui/monitoring_tab.py (1546 dong) tach thanh presentation/monitoring/**
  (container + 7 tab/card + shared helper), ui/monitoring_tab.py con lai
  re-export shim de app.py khong doi.
- infrastructure/telemetry/audit_logger.py: CanonicalAuditLogger, core/audit_log.py
  thanh wrapper mong, tuong thich nguoc 100% voi schema .jsonl cu.
- application/monitoring/monitoring_query_service.py: MonitoringQueryService
  read-only, filter/sort/pagination, khong import PySide6.
- Go circular import model_pricing<->usage_tracker va agent_security<->
  agent_security_alert (core/agent_security_types.py moi).
- infrastructure/sandbox/sandbox_capabilities.py: SandboxCapabilityMatrix
  theo OS (Windows/Linux/macOS), chua dau noi vao core/sandbox_manager.py.
- conftest.py: sua loi checkout khong ten cowork_local khien pytest import
  nham thu muc khac.
- 77 test moi, 167/167 pass. QA da xac nhan UI/business logic khong doi
  (xem evidence/report/unified_report.html).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

core/usage_tracker.py

@@ -19,6 +19,7 @@ from pathlib import Path
 from typing import Any, Dict, List, Optional
 
 from ..config import CONFIG_DIR
+from . import model_pricing as mp
 
 USAGE_DIR = CONFIG_DIR / "usage"
 
@@ -49,6 +50,18 @@ def set_context(source: str, label: str = "") -> None:
     _local.label = label
 
 
+def current_context() -> tuple:
+    """The ``(source, label)`` currently tagged on THIS thread.
+
+    Public counterpart to :func:`set_context`, added for
+    ``infrastructure/telemetry/usage_sink.py``: a subscriber that needs to
+    attribute one event to a different surface must be able to save the
+    caller's context and put it back afterwards, instead of leaving the worker
+    thread permanently retagged.
+    """
+    return getattr(_local, "source", "") or "", getattr(_local, "label", "") or ""
+
+
 # ---- per-thread usage accumulator -----------------------------------------
 # A step/run that wants to know its OWN token/cost (not the all-time file total)
 # calls begin_accumulation(), reads accumulated() before/after a unit of work,
@@ -397,7 +410,6 @@ def set_budget(config, amount: float, currency: Optional[str] = None) -> None:
     order and ``budget_set_at`` only has 1-second resolution, so a timestamp
     cutoff could mis-include/exclude an event recorded in that same second —
     the count baseline is exact regardless of timing."""
-    from . import model_pricing as mp
     usage = config.data.setdefault("usage", {})
     ccy = (currency or usage.get("currency") or "USD").upper()
     usage["budget_amount_usd"] = mp.convert(float(amount or 0), ccy, "USD", config)