fix(events): normalize naive datetimes to UTC in HTTP route

All datetime parsing now uses _parse_dt() which adds UTC tzinfo when
none is present, matching the fix already applied in tools.py. This
prevents asyncpg errors when comparing naive datetimes against
TIMESTAMPTZ columns — the root cause of events not appearing in the
calendar view.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/fabledassistant/routes/events.py

@@ -1,7 +1,7 @@
 """Calendar events REST API."""
 from __future__ import annotations
 
-from datetime import datetime
+from datetime import datetime, timezone
 
 from quart import Blueprint, g, jsonify, request
 
@@ -11,6 +11,14 @@ import fabledassistant.services.events as events_svc
 events_bp = Blueprint("events", __name__, url_prefix="/api/events")
 
 
+def _parse_dt(value: str) -> datetime:
+    """Parse ISO 8601 datetime string, ensuring UTC-awareness."""
+    dt = datetime.fromisoformat(value.replace("Z", "+00:00"))
+    if dt.tzinfo is None:
+        dt = dt.replace(tzinfo=timezone.utc)
+    return dt
+
+
 def _get_current_user_id() -> int:
     return g.user.id
 
@@ -23,8 +31,8 @@ async def list_events():
     if not date_from_str or not date_to_str:
         return jsonify({"error": "from and to query params are required"}), 400
     try:
-        date_from = datetime.fromisoformat(date_from_str)
-        date_to = datetime.fromisoformat(date_to_str)
+        date_from = _parse_dt(date_from_str)
+        date_to = _parse_dt(date_to_str)
     except ValueError:
         return jsonify({"error": "Invalid datetime format"}), 400
     events = await events_svc.list_events(
@@ -42,8 +50,8 @@ async def create_event():
     if not data.get("title") or not data.get("start_dt"):
         return jsonify({"error": "title and start_dt are required"}), 400
     try:
-        start_dt = datetime.fromisoformat(data["start_dt"])
-        end_dt = datetime.fromisoformat(data["end_dt"]) if data.get("end_dt") else None
+        start_dt = _parse_dt(data["start_dt"])
+        end_dt = _parse_dt(data["end_dt"]) if data.get("end_dt") else None
     except ValueError:
         return jsonify({"error": "Invalid datetime format"}), 400
     event = await events_svc.create_event(
@@ -90,7 +98,7 @@ async def update_event(event_id: int):
     for dt_field in ("start_dt", "end_dt"):
         if dt_field in data and data[dt_field]:
             try:
-                fields[dt_field] = datetime.fromisoformat(data[dt_field])
+                fields[dt_field] = _parse_dt(data[dt_field])
             except ValueError:
                 return jsonify({"error": f"Invalid datetime for {dt_field}"}), 400
     event = await events_svc.update_event(