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/slots/services/slots.py

@@ -0,0 +1,64 @@
+
+from __future__ import annotations
+from datetime import time
+from typing import Sequence
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from models.calendars import CalendarSlot
+
+class SlotError(ValueError):
+    pass
+
+def _b(v):
+    if isinstance(v, bool):
+        return v
+    s = str(v).lower()
+    return s in {"1","true","t","yes","y","on"}
+
+async def list_slots(sess: AsyncSession, calendar_id: int) -> Sequence[CalendarSlot]:
+    res = await sess.execute(
+        select(CalendarSlot)
+        .where(CalendarSlot.calendar_id == calendar_id, CalendarSlot.deleted_at.is_(None))
+        .order_by(CalendarSlot.time_start.asc(), CalendarSlot.id.asc())
+    )
+    return res.scalars().all()
+
+async def create_slot(
+    sess: AsyncSession,
+    calendar_id: int,
+    *,
+    name: str,
+    description: str | None,
+    days: dict,
+    time_start: time,
+    time_end: time,
+    cost: float | None,
+    flexible: bool = False,   # NEW
+):
+    if not name:
+        raise SlotError("name is required")
+
+    if not time_start or not time_end or time_end <= time_start:
+        raise SlotError("time range invalid")
+
+    slot = CalendarSlot(
+        calendar_id=calendar_id,
+        name=name,
+        description=(description or None),
+        mon=_b(days.get("mon")),
+        tue=_b(days.get("tue")),
+        wed=_b(days.get("wed")),
+        thu=_b(days.get("thu")),
+        fri=_b(days.get("fri")),
+        sat=_b(days.get("sat")),
+        sun=_b(days.get("sun")),
+        time_start=time_start,
+        time_end=time_end,
+        cost=cost,
+        flexible=flexible,   # NEW
+    )
+    sess.add(slot)
+    await sess.flush()
+    return slot