fix(ticketing): render email templates without a permission check

[harshtandiya]

What changed

Ticket, booking-confirmation and sponsor pitch-deck emails all rendered their
Email Template through frappe.email...get_email_template(), which is
whitelisted and reads the template as the session user. Read on Email Template
is granted to Desk User and System Manager only, so every attendee-facing
send raised PermissionError — guests booking publicly, logged-in Website
Users booking for themselves, and Buzz Users raising a sponsorship enquiry.
Both on_submit handlers swallow the exception, so the booking succeeded and
the email silently never went out; str(PermissionError) is empty, which is
why the Error Log entry had no message.

All three call sites now go through buzz.utils.render_email_template(), which
formats the template off the doc directly.

Only shows up on a frappe carrying the check_permission("read") inside
get_email_template() — our local bench (develop @ 80d9c31) predates it,
so this reproduces on CI and production, not necessarily on your machine.

Not touched: the blanket except Exception + log_error(str(e)) in
EventTicket.on_submit that hid this. Worth narrowing separately.

Demo

No UI change. skip-demo.

Testing

• TestRenderEmailTemplate — a Website User with no read access on Email
  Template still gets a rendered subject and message. Goes red on any frappe
  with the permission check if the whitelisted helper comes back.
• TestGuestTicketEmail — guest ticket submit renders from the event template.
• bench run-tests: event_ticket 12, event_booking 40, booking API 33,
  sponsorship_enquiry 4 — all pass.

[greptile-apps]

Greptile Summary

The PR replaces Frappe’s permission-checked email-template helper with an internal renderer so guest and Website User workflows can send configured emails.

• Adds a shared render_email_template utility that formats an Email Template document directly.
• Migrates ticket, booking-confirmation, and sponsorship pitch-deck emails to the utility.
• Adds coverage for rendering without Email Template read permission and sending a guest ticket email.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete blocking or independently actionable non-blocking issue identified.

The changed call sites retain their existing server-controlled template selection and email behavior while avoiding the permission-checked rendering path that prevented guest-facing emails.

Important Files Changed

Filename	Overview
buzz/utils.py	Adds the permission-independent template renderer used by guest-facing email flows; no concrete defect was identified.
buzz/ticketing/doctype/event_ticket/event_ticket.py	Routes ticket-template rendering through the new helper while preserving template selection, message construction, and attachments.
buzz/ticketing/doctype/event_booking/event_booking.py	Routes booking-confirmation rendering through the new helper without changing fallback precedence or recipient handling.
buzz/proposals/doctype/sponsorship_enquiry/sponsorship_enquiry.py	Routes configured sponsorship pitch-deck templates through the new helper while retaining existing send behavior.
buzz/ticketing/doctype/event_ticket/test_event_ticket.py	Adds regression coverage for unprivileged template rendering and guest ticket-email delivery.

_{Reviews (1): Last reviewed commit: "test(ticketing): pin email rendering to ..." | Re-trigger Greptile}

[github-actions]

Backport failed for main, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin main
git worktree add -d .worktree/backport-369-to-main origin/main
cd .worktree/backport-369-to-main
git switch --create backport-369-to-main
git cherry-pick -x b724d9158102db2ce9301bf13ff465d2a158fa4e