Add password change, rename Viewer→Commissioner, fix login logo

- Rename VIEWER role to COMMISSIONER throughout (schema, middleware,
  admin layout, users page); add psql pre-migration step in entrypoint
  to rename the PostgreSQL enum value without data loss
- Install postgresql-client in Docker runner stage for psql access
- Login page: fetch sbLogo from settings API instead of hardcoded path
- Password change for all authenticated users:
  - New PATCH /api/users/me endpoint (verifies current password, hashes new)
  - Change Password button/modal on /my-squares page
  - Change Password link in admin sidebar (links to /my-squares)
  - New password_change email template (seeded, editable in admin)
  - sendPasswordChangedEmail auto-email triggered on change

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

prisma/seed.ts

@@ -95,6 +95,11 @@ async function main() {
       subject: 'Final Results - {{eventName}}',
       body: 'Hi {{name}},\n\nThe game is over! Here are the final results for {{eventName}}:\n\nWinners:\n{{winners}}\n\nCongratulations to all the winners!\n\nThank you for participating in this year\'s Super Bowl Squares. We hope you had a great time!\n\nView the final board at: {{gameUrl}}\n\n{{commissioner}}',
     },
+    {
+      name: 'password_change',
+      subject: 'Password Changed - {{eventName}}',
+      body: 'Hi {{name}},\n\nYour password for {{eventName}} Squares has been changed successfully.\n\nIf you did not make this change, please contact the commissioner immediately.\n\nYou can log in at: {{gameUrl}}/login\n\n{{commissioner}}',
+    },
   ];
 
   for (const template of templates) {