Run background jobs on a pg-boss queue; add e2e tests, CI and deploy script

Timed jobs move from in-process timers to a job registry run by pg-boss:
once per schedule across processes, retries, run history, cron schedules
in the church timezone, and an admin Background jobs page with Run now.
Playwright end-to-end tests run against their own seeded database. A
Gitea Actions workflow runs backend tests, frontend checks and the e2e
tests, and deploys v* tags with scripts/deploy.sh once secrets are set.
Also fixes the at-the-door check-in count for multi-day tickets.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitignore

@@ -39,4 +39,9 @@ hope-events-deployment-setup.txt
 
 # runtime data stores (mutated by the running app, not source)
 backend/data/scheduled-emails.json
-backend/data/banner.json
+backend/data/banner.json
+# end-to-end tests
+e2e/.data/
+e2e/report/
+e2e/test-results/
+frontend/.next-e2e/