feat: initialize events app with calendars, slots, tickets, and internal API

Extract events/calendar functionality into standalone microservice:
- app.py and events_api.py from apps/events/
- Calendar blueprints (calendars, calendar, calendar_entries, calendar_entry, day, slots, slot, ticket_types, ticket_type)
- Templates for all calendar/event views including admin
- Dockerfile (APP_MODULE=app:app, IMAGE=events)
- entrypoint.sh (no Alembic - migrations managed by blog app)
- Gitea CI workflow for build and deploy

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

bp/calendar/services/calendar.py

@@ -0,0 +1,28 @@
+from __future__ import annotations
+
+
+from models.calendars import Calendar
+from ...calendars.services.calendars import CalendarError
+
+async def update_calendar_config(sess, calendar_id: int, *, description: str | None, slots: list | None):
+    """Update description and slots for a calendar."""
+    cal = await sess.get(Calendar, calendar_id)
+    if not cal:
+        raise CalendarError(f"Calendar {calendar_id} not found.")
+    cal.description = (description or '').strip() or None
+    # Validate slots shape a bit
+    norm_slots: list[dict] = []
+    if slots:
+        for s in slots:
+            if not isinstance(s, dict):
+                continue
+            norm_slots.append({
+                "days": str(s.get("days", ""))[:7].lower(),
+                "time_from": str(s.get("time_from", ""))[:5],
+                "time_to": str(s.get("time_to", ""))[:5],
+                "cost_name": (s.get("cost_name") or "")[:64],
+                "description": (s.get("description") or "")[:255],
+            })
+    cal.slots = norm_slots or None
+    await sess.flush()
+    return cal