feat: event cards in chat/briefing, upcoming events on dashboard, briefing uses internal store

- ToolCallCard: event list items replaced with rich clickable cards (color dot,
  title, time, location); clicking opens EventSlideOver for edit/delete; single
  create/update events in header are also clickable; updated all event types to
  use start_dt/end_dt fields from internal store
- HomeView: new upcoming events widget shows today + next 7 days as a card grid
  above the hero project; clicking any card opens EventSlideOver inline
- briefing_pipeline: _gather_internal now queries the internal events store for
  today's events; CalDAV events are still appended (deduped) if configured

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

src/fabledassistant/services/briefing_pipeline.py

@@ -162,17 +162,36 @@ async def _gather_internal(user_id: int) -> dict:
         logger.warning("Failed to gather tasks for briefing", exc_info=True)
         overdue, due_today, high_priority = [], [], []
 
-    # Calendar events today
-    calendar_events = []
+    # Calendar events today — internal store
+    calendar_events: list[str] = []
+    try:
+        from fabledassistant.services.events import list_events as list_internal_events
+        today_date = date.today()
+        day_start = datetime(today_date.year, today_date.month, today_date.day, 0, 0, 0)
+        day_end = datetime(today_date.year, today_date.month, today_date.day, 23, 59, 59)
+        internal_events = await list_internal_events(
+            user_id=user_id, date_from=day_start, date_to=day_end
+        )
+        for e in internal_events:
+            if e.all_day:
+                time_str = "all day"
+            elif e.start_dt:
+                time_str = e.start_dt.strftime("%-I:%M %p")
+            else:
+                time_str = "unknown time"
+            calendar_events.append(f"{e.title} at {time_str}")
+    except Exception:
+        logger.warning("Failed to gather internal calendar events for briefing", exc_info=True)
+    # Also pull CalDAV events (deduped)
     try:
         if await is_caldav_configured(user_id):
-            events = await list_events(user_id, start=today, end=today)
-            calendar_events = [
-                f"{e.get('summary', 'Event')} at {e.get('dtstart', 'unknown time')}"
-                for e in (events or [])
-            ]
+            caldav_evs = await list_events(user_id, start=today, end=today)
+            for e in (caldav_evs or []):
+                summary = f"{e.get('summary', 'Event')} at {e.get('dtstart', 'unknown time')}"
+                if summary not in calendar_events:
+                    calendar_events.append(summary)
     except Exception:
-        logger.warning("Failed to gather calendar events for briefing", exc_info=True)
+        logger.warning("Failed to gather CalDAV calendar events for briefing", exc_info=True)
 
     # Projects: active projects
     projects_summary = []