feat: pagination totals, request logging, data retention

Add shared paginate() helper with total count to all list endpoints.
Add request logging middleware (method, path, status, duration, IP).
Add data retention service with configurable thresholds and CLI command.

src/esp32_web/api/events.py

@@ -1,7 +1,7 @@
 """Event endpoints."""
 from datetime import datetime, timedelta, UTC
 from flask import request
-from . import bp
+from . import bp, paginate
 from ..models import Event
 from ..extensions import db
 
@@ -12,8 +12,6 @@ def list_events():
     event_type = request.args.get('type')
     sensor_id = request.args.get('sensor_id', type=int)
     hours = request.args.get('hours', 24, type=int)
-    limit = min(int(request.args.get('limit', 100)), 1000)
-    offset = int(request.args.get('offset', 0))
 
     since = datetime.now(UTC) - timedelta(hours=hours)
     query = db.select(Event).where(Event.timestamp >= since).order_by(Event.timestamp.desc())
@@ -23,7 +21,6 @@ def list_events():
     if sensor_id:
         query = query.where(Event.sensor_id == sensor_id)
 
-    query = query.limit(limit).offset(offset)
-    events = db.session.scalars(query).all()
-
-    return {'events': [e.to_dict() for e in events], 'limit': limit, 'offset': offset}
+    result = paginate(query, Event.to_dict)
+    return {'events': result['items'], 'total': result['total'],
+            'limit': result['limit'], 'offset': result['offset']}