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/calendars/services/calendars.py

@@ -0,0 +1,104 @@
+from __future__ import annotations
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from models.calendars import Calendar
+from models.ghost_content import Post  # for FK existence checks
+import unicodedata
+import re
+
+
+class CalendarError(ValueError):
+    """Base error for calendar service operations."""
+
+from suma_browser.app.utils import (
+    utcnow
+)
+
+def slugify(value: str, max_len: int = 255) -> str:
+    """
+    Make a URL-friendly slug:
+    - lowercase
+    - remove accents
+    - replace any non [a-z0-9]+ with '-'
+    - no forward slashes
+    - collapse multiple dashes
+    - trim leading/trailing dashes
+    """
+    if value is None:
+        value = ""
+    # normalize accents -> ASCII
+    value = unicodedata.normalize("NFKD", value)
+    value = value.encode("ascii", "ignore").decode("ascii")
+    value = value.lower()
+
+    # explicitly block forward slashes
+    value = value.replace("/", "-")
+
+    # replace non-alnum with hyphen
+    value = re.sub(r"[^a-z0-9]+", "-", value)
+    # collapse multiple hyphens
+    value = re.sub(r"-{2,}", "-", value)
+    # trim hyphens and enforce length
+    value = value.strip("-")[:max_len].strip("-")
+
+    # fallback if empty
+    return value or "calendar"
+
+
+async def soft_delete(sess: AsyncSession, post_slug: str, calendar_slug: str) -> bool:
+    cal = (
+        await sess.execute(
+            select(Calendar)
+            .join(Post, Calendar.post_id == Post.id)
+            .where(
+                Post.slug == post_slug,
+                Calendar.slug == calendar_slug,
+                Calendar.deleted_at.is_(None),
+            )
+        )
+    ).scalar_one_or_none()
+
+    if not cal:
+        return False
+
+    cal.deleted_at = utcnow()
+    await sess.flush()
+    return True
+
+async def create_calendar(sess: AsyncSession, post_id: int, name: str) -> Calendar:
+    """
+    Create a calendar for a post. Name must be unique per post.
+    If a calendar with the same (post_id, name) exists but is soft-deleted,
+    it will be revived (deleted_at=None).
+    """
+    name = (name or "").strip()
+    if not name:
+        raise CalendarError("Calendar name must not be empty.")
+    slug=slugify(name)
+
+    # Ensure post exists (avoid silent FK errors in some DBs)
+    post = (await sess.execute(select(Post.id).where(Post.id == post_id))).scalar_one_or_none()
+    if not post:
+        raise CalendarError(f"Post {post_id} does not exist.")
+
+    # Look for existing (including soft-deleted)
+    q = await sess.execute(
+        select(Calendar).where(Calendar.post_id == post_id, Calendar.name == name)
+    )
+    existing = q.scalar_one_or_none()
+
+    if existing:
+        if existing.deleted_at is not None:
+            existing.deleted_at = None  # revive
+            await sess.flush()
+            return existing
+        raise CalendarError(f'Calendar with slug "{slug}" already exists for post {post_id}.')
+
+    cal = Calendar(post_id=post_id, name=name, slug=slug)
+    sess.add(cal)
+    await sess.flush()
+    return cal
+
+