ops(triage): PR-4B-Diagnose-EventKindHint-Layer-A — diagnostic logging (no behavior change)

Layer-A Diagnose only. classify_worker.py:691 직전에 event_kind_hint 의
raw/normalized/in_valid/confidence 값 capture (logger.info 5줄 insert,
lazy formatting + %r repr). guard 통과 X 의 specific root cause (A1 field
부재 / A2 빈 string / A3 invalid enum) 확정용.

specific fix (default note / enum mapping / prompt 강화) 는 별 PR-4B-Fix-EventKindHint-Apply.
Apply PR closure gate 에 logging cleanup (info → DEBUG 또는 제거) 흡수.

plan: ~/.claude/plans/c-1-pr-infra-drift-1-phase-1b-linear-frost.md
backup: app/workers/classify_worker.py.pre-4b-eventkind-logging.20260517

app/workers/classify_worker.py

@@ -687,6 +687,14 @@ async def _apply_triage_result(
         # 허용 enum 외 값이면 무시 (DB enum 제약). AI worker 는 events row 직접 생성 X.
         valid_kinds = {"note", "task", "calendar_event", "activity_log", "reference"}
         hint = (triage_out.event_kind_hint or "").strip().lower() or None
+        logger.info(
+            "[triage] event_kind_hint id=%s raw=%r normalized=%r in_valid=%s confidence=%r",
+            document_id,
+            triage_out.event_kind_hint,
+            hint,
+            hint in valid_kinds,
+            triage_out.event_kind_confidence,
+        )
         if hint in valid_kinds:
             doc.ai_event_kind = hint
             try: