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/rag/retrieval/dataset_retrieval.py

@@ -55,7 +55,7 @@ from core.rag.retrieval.template_prompts import (
     METADATA_FILTER_USER_PROMPT_2,
     METADATA_FILTER_USER_PROMPT_3,
 )
-from core.telemetry import TelemetryContext, TelemetryEvent, TelemetryFacade
+from core.telemetry import TelemetryContext, TelemetryEvent, TelemetryFacade, TraceTaskName
 from core.tools.signature import sign_upload_file
 from core.tools.utils.dataset_retriever.dataset_retriever_base_tool import DatasetRetrieverBaseTool
 from extensions.ext_database import db
@@ -731,7 +731,7 @@ class DatasetRetrieval:
             app_config = self.application_generate_entity.app_config if self.application_generate_entity else None
             TelemetryFacade.emit(
                 TelemetryEvent(
-                    name="dataset_retrieval",
+                    name=TraceTaskName.DATASET_RETRIEVAL_TRACE,
                     context=TelemetryContext(
                         tenant_id=app_config.tenant_id if app_config else None,
                         app_id=app_config.app_id if app_config else None,