feat: ticket purchase flow, QR display, and admin check-in

Ticket purchase:
- tickets blueprint with routes for my tickets list, ticket detail with QR
- Buy tickets form on entry detail page (HTMX-powered)
- Ticket services: create, query, availability checking

Admin check-in:
- ticket_admin blueprint with dashboard, lookup, and check-in routes
- QR scanner/lookup interface with real-time search
- Per-entry ticket list view
- Check-in transitions ticket state to checked_in

Internal API:
- GET /internal/events/tickets endpoint for cross-app queries
- POST /internal/events/tickets/<code>/checkin for programmatic check-in

Template fixes:
- All templates updated: blog.post.calendars.* → calendars.*
- Removed slug=post.slug parameters (standalone events service)

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

bp/tickets/routes.py

@@ -0,0 +1,181 @@
+"""
+Tickets blueprint — user-facing ticket views and QR codes.
+
+Routes:
+  GET  /tickets/              — My tickets list
+  GET  /tickets/<code>/       — Ticket detail with QR code
+  POST /tickets/buy/          — Purchase tickets for an entry
+"""
+from __future__ import annotations
+
+import logging
+
+from quart import (
+    Blueprint, g, request, render_template, make_response,
+)
+from sqlalchemy import select
+from sqlalchemy.orm import selectinload
+
+from models.calendars import CalendarEntry
+from shared.cart_identity import current_cart_identity
+from suma_browser.app.redis_cacher import clear_cache
+
+from .services.tickets import (
+    create_ticket,
+    get_ticket_by_code,
+    get_user_tickets,
+    get_available_ticket_count,
+    get_tickets_for_entry,
+)
+
+logger = logging.getLogger(__name__)
+
+
+def register() -> Blueprint:
+    bp = Blueprint("tickets", __name__, url_prefix="/tickets")
+
+    @bp.get("/")
+    async def my_tickets():
+        """List all tickets for the current user/session."""
+        from suma_browser.app.utils.htmx import is_htmx_request
+
+        ident = current_cart_identity()
+        tickets = await get_user_tickets(
+            g.s,
+            user_id=ident["user_id"],
+            session_id=ident["session_id"],
+        )
+
+        if not is_htmx_request():
+            html = await render_template(
+                "_types/tickets/index.html",
+                tickets=tickets,
+            )
+        else:
+            html = await render_template(
+                "_types/tickets/_main_panel.html",
+                tickets=tickets,
+            )
+
+        return await make_response(html, 200)
+
+    @bp.get("/<code>/")
+    async def ticket_detail(code: str):
+        """View a single ticket with QR code."""
+        from suma_browser.app.utils.htmx import is_htmx_request
+
+        ticket = await get_ticket_by_code(g.s, code)
+        if not ticket:
+            return await make_response("Ticket not found", 404)
+
+        # Verify ownership
+        ident = current_cart_identity()
+        if ident["user_id"] is not None:
+            if ticket.user_id != ident["user_id"]:
+                return await make_response("Ticket not found", 404)
+        elif ident["session_id"] is not None:
+            if ticket.session_id != ident["session_id"]:
+                return await make_response("Ticket not found", 404)
+        else:
+            return await make_response("Ticket not found", 404)
+
+        if not is_htmx_request():
+            html = await render_template(
+                "_types/tickets/detail.html",
+                ticket=ticket,
+            )
+        else:
+            html = await render_template(
+                "_types/tickets/_detail_panel.html",
+                ticket=ticket,
+            )
+
+        return await make_response(html, 200)
+
+    @bp.post("/buy/")
+    @clear_cache(tag="calendars", tag_scope="all")
+    async def buy_tickets():
+        """
+        Purchase tickets for a calendar entry.
+        Creates ticket records with state='reserved' (awaiting payment).
+
+        Form fields:
+          entry_id     — the calendar entry ID
+          ticket_type_id (optional) — specific ticket type
+          quantity     — number of tickets (default 1)
+        """
+        form = await request.form
+
+        entry_id_raw = form.get("entry_id", "").strip()
+        if not entry_id_raw:
+            return await make_response("Entry ID required", 400)
+
+        try:
+            entry_id = int(entry_id_raw)
+        except ValueError:
+            return await make_response("Invalid entry ID", 400)
+
+        # Load entry
+        entry = await g.s.scalar(
+            select(CalendarEntry)
+            .where(
+                CalendarEntry.id == entry_id,
+                CalendarEntry.deleted_at.is_(None),
+            )
+            .options(selectinload(CalendarEntry.ticket_types))
+        )
+        if not entry:
+            return await make_response("Entry not found", 404)
+
+        if entry.ticket_price is None:
+            return await make_response("Tickets not available for this entry", 400)
+
+        # Check availability
+        available = await get_available_ticket_count(g.s, entry_id)
+        quantity = int(form.get("quantity", 1))
+        if quantity < 1:
+            quantity = 1
+
+        if available is not None and quantity > available:
+            return await make_response(
+                f"Only {available} ticket(s) remaining", 400
+            )
+
+        # Ticket type (optional)
+        ticket_type_id = None
+        tt_raw = form.get("ticket_type_id", "").strip()
+        if tt_raw:
+            try:
+                ticket_type_id = int(tt_raw)
+            except ValueError:
+                pass
+
+        ident = current_cart_identity()
+
+        # Create tickets
+        created = []
+        for _ in range(quantity):
+            ticket = await create_ticket(
+                g.s,
+                entry_id=entry_id,
+                ticket_type_id=ticket_type_id,
+                user_id=ident["user_id"],
+                session_id=ident["session_id"],
+                state="reserved",
+            )
+            created.append(ticket)
+
+        # Re-check availability for display
+        remaining = await get_available_ticket_count(g.s, entry_id)
+        all_tickets = await get_tickets_for_entry(g.s, entry_id)
+
+        html = await render_template(
+            "_types/tickets/_buy_result.html",
+            entry=entry,
+            created_tickets=created,
+            remaining=remaining,
+            all_tickets=all_tickets,
+        )
+        return await make_response(html, 200)
+
+    return bp