refactor(telemetry): migrate to type-safe enum-based event routing with centralized enterprise filtering

Changes:
- Change TelemetryEvent.name from str to TraceTaskName enum for type safety
- Remove hardcoded trace_task_name_map from facade (no mapping needed)
- Add centralized enterprise-only filter in TelemetryFacade.emit()
- Rename is_telemetry_enabled() to is_enterprise_telemetry_enabled()
- Update all 11 call sites to pass TraceTaskName enum values
- Remove redundant enterprise guard from draft_trace.py
- Add unit tests for TelemetryFacade.emit() routing (6 tests)
- Add unit tests for TraceQueueManager telemetry guard (5 tests)
- Fix test fixture scoping issue for full test suite compatibility
- Fix tenant_id handling in agent tool callback handler

Benefits:
- 100% type-safe: basedpyright catches errors at compile time
- No string literals: eliminates entire class of typo bugs
- Single point of control: centralized filtering in facade
- All guards removed except facade
- Zero regressions: 4887 tests passing

Verification:
- make lint: PASS
- make type-check: PASS (0 errors, 0 warnings)
- pytest: 4887 passed, 8 skipped

api/core/moderation/input_moderation.py

@@ -7,7 +7,7 @@ from core.moderation.base import ModerationAction, ModerationError
 from core.moderation.factory import ModerationFactory
 from core.ops.ops_trace_manager import TraceQueueManager
 from core.ops.utils import measure_time
-from core.telemetry import TelemetryContext, TelemetryEvent, TelemetryFacade
+from core.telemetry import TelemetryContext, TelemetryEvent, TelemetryFacade, TraceTaskName
 
 logger = logging.getLogger(__name__)
 
@@ -51,7 +51,7 @@ class InputModeration:
         if trace_manager:
             TelemetryFacade.emit(
                 TelemetryEvent(
-                    name="moderation",
+                    name=TraceTaskName.MODERATION_TRACE,
                     context=TelemetryContext(tenant_id=tenant_id, app_id=app_id),
                     payload={
                         "message_id": message_id,