Add permanent user deletion endpoint with cascade cleanup and trash icon button in admin panel

Implemented DELETE `/admin/users/{user_id}/permanent` endpoint with safeguards preventing self-deletion and blocking deletion of game hosts. Added cascade deletion of user's game memberships, chips, sheet states, and invite tokens, with winner references nullified. Added trash icon button (🗑) to admin user rows with bilingual confirmation dialog and error handling for game ownership conflicts. Adjusted

frontend/src/styles/styles.js

@@ -189,7 +189,6 @@ export const styles = {
   },
   userRow: {
     display: "grid",
-    gridTemplateColumns: "1fr 80px 90px",
     gap: 8,
     padding: 10,
     borderRadius: 12,