feat(tokens): allow permanent deletion of revoked tokens

Add POST /admin/tokens/{id}/delete endpoint that permanently removes
a token from the database (only if already revoked). Add delete button
in backoffice UI for revoked tokens.

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

apps/api/src/openapi.rs

@@ -31,6 +31,7 @@ use utoipa::OpenApi;
         crate::tokens::list_tokens,
         crate::tokens::create_token,
         crate::tokens::revoke_token,
+        crate::tokens::delete_token,
         crate::settings::get_settings,
         crate::settings::get_setting,
         crate::settings::update_setting,