fix(km): normalize legacy timestamps

apps/api/src/repositories/knowledge_repository.py

@@ -27,6 +27,7 @@ from src.models.knowledge import (
     KnowledgeEntry,
     KnowledgeEntryCreate,
 )
+from src.utils.timezone import now_taipei
 
 logger = structlog.get_logger(__name__)
 
@@ -199,6 +200,13 @@ def _normalize_tags(value: object) -> list[str]:
     return [str(value).strip()] if str(value).strip() else []
 
 
+def _normalize_int(value: object, *, fallback: int = 0) -> int:
+    try:
+        return int(value or fallback)
+    except (TypeError, ValueError):
+        return fallback
+
+
 def _normalized_category_expr():
     return func.coalesce(
         func.nullif(func.trim(KnowledgeEntryRecord.category), ""),
@@ -612,10 +620,10 @@ class KnowledgeDBRepository:
             # P1-1 M3 2026-04-28 ogt + Claude Sonnet 4.6: 冪等 key
             path_type=get("path_type"),
             symptoms_hash=get("symptoms_hash"),
-            view_count=int(get("view_count") or 0),
+            view_count=_normalize_int(get("view_count")),
             created_by=get("created_by"),
-            created_at=get("created_at"),
-            updated_at=get("updated_at"),
+            created_at=get("created_at") or now_taipei(),
+            updated_at=get("updated_at") or get("created_at") or now_taipei(),
         )