feat(events): recurring expansion, CalDAV pull sync, past search, reminders

- RRULE expansion: list_events now expands recurring events into
  individual occurrences within the query window using python-dateutil
- CalDAV pull sync: new caldav_sync.py + POST /api/events/sync route;
  imports remote events into the internal store by caldav_uid
- Past event search: search_events accepts include_past=true to search
  historical events; exposed in the LLM tool definition
- Internal reminders: migration 0037 adds reminder_minutes +
  reminder_sent_at columns; event_scheduler.py checks every 5 min and
  fires push notifications; CalDAV sync job runs hourly
- reminder_minutes now stored and returned in create/update routes + tools

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

src/fabledassistant/services/tools.py

@@ -695,6 +695,10 @@ _CORE_TOOLS = [
                         "type": "string",
                         "description": "Search keyword to match against event titles, locations, and descriptions",
                     },
+                    "include_past": {
+                        "type": "boolean",
+                        "description": "Set to true to include past events in results (default: future events only)",
+                    },
                 },
                 "required": ["query"],
             },
@@ -744,6 +748,10 @@ _CORE_TOOLS = [
                         "type": "string",
                         "description": "New iCalendar RRULE",
                     },
+                    "reminder_minutes": {
+                        "type": "integer",
+                        "description": "Reminder N minutes before the event. Pass 0 to remove an existing reminder.",
+                    },
                 },
                 "required": ["query"],
             },
@@ -1471,7 +1479,7 @@ async def execute_tool(
                 "type": "events",
                 "data": {
                     "count": len(events),
-                    "events": [e.to_dict() for e in events],
+                    "events": events,
                 },
             }
 
@@ -1479,6 +1487,7 @@ async def execute_tool(
             events = await events_search_events(
                 user_id=user_id,
                 query=arguments.get("query", ""),
+                include_past=arguments.get("include_past", False),
             )
             return {
                 "success": True,
@@ -1502,6 +1511,9 @@ async def execute_tool(
                     fields[str_field] = arguments[str_field]
             if arguments.get("all_day") is not None:
                 fields["all_day"] = arguments["all_day"]
+            if "reminder_minutes" in arguments:
+                rm = arguments["reminder_minutes"]
+                fields["reminder_minutes"] = None if rm == 0 else rm
             for dt_field, key in (("start_dt", "start"), ("end_dt", "end")):
                 val = arguments.get(key)
                 if val: