feat(setup): event-types step in first-run wizard + un-hardcode event type deps (#800)

Fresh installs can now shape the event-type catalog during the setup
wizard — rename, delete or replace the seeded defaults while nothing
references them. On existing installs system types stay protected.

- New wizard step between features and config: edit name/URL prefix,
  remove, or add types; defaults shown as recommendations
- setup_wizard_completed app setting (migration 161): seeded true when
  an admin already exists, false on fresh installs; POST /api/setup/
  complete (adminAuth) flips it when the wizard finishes
- deleteEventType: system types deletable only while the flag is unset;
  in-use check extended to quotes; per-type reminder template
  (event_reminder_<slug>) is deleted with the type
- reminder-template self-heal no longer resurrects templates for slugs
  removed from the catalog
- v1 API event creation validates event_type against the live catalog
  instead of a hardcoded whitelist (custom types were rejected; the
  never-seeded 'family' slug is no longer silently accepted)
- contract→event conversion resolves the event type via
  crm_default_event_type / resolveDefaultEventType instead of
  hardcoding 'wedding' (resolveDefaultEventType moved from quoteService
  to eventTypeService for reuse)

backend/src/routes/setup.js

@@ -10,6 +10,7 @@ const { body, validationResult } = require('express-validator');
 const setupService = require('../services/setupService');
 const { getClientIp } = require('../utils/requestIp');
 const { setAdminAuthCookie } = require('../utils/tokenUtils');
+const { adminAuth } = require('../middleware/auth');
 const logger = require('../utils/logger');
 
 const router = express.Router();
@@ -79,4 +80,19 @@ router.post('/admin', [
   }
 });
 
+// Wizard finish marker — unlike the endpoints above this one runs AFTER the
+// admin exists (the wizard is authenticated from the account step onward), so
+// it takes the normal admin auth. One-way: while the flag is unset the seeded
+// SYSTEM event types may be deleted from the wizard's event-types step; once
+// set they are permanently protected (#800).
+router.post('/complete', adminAuth, async (req, res) => {
+  try {
+    await setupService.markSetupWizardCompleted();
+    res.json({ completed: true });
+  } catch (err) {
+    logger.error('[setup] markSetupWizardCompleted failed', { error: err.message });
+    res.status(500).json({ error: 'Failed to mark setup complete' });
+  }
+});
+
 module.exports = router;