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/day/admin/routes.py

@@ -0,0 +1,28 @@
+from __future__ import annotations
+
+from quart import (
+    render_template, make_response, Blueprint
+)
+
+
+from suma_browser.app.authz import require_admin
+
+
+def register():
+    bp = Blueprint("admin", __name__, url_prefix='/admin')
+    
+    # ---------- Pages ----------
+    @bp.get("/")
+    @require_admin
+    async def admin(year: int, month: int, day: int, **kwargs):
+        from suma_browser.app.utils.htmx import is_htmx_request
+
+        # Determine which template to use based on request type
+        if not is_htmx_request():
+            # Normal browser request: full page with layout
+            html = await render_template("_types/day/admin/index.html")
+        else:
+            html = await render_template("_types/day/admin/_oob_elements.html")
+
+        return await make_response(html)
+    return bp