fix: resolve clippy warnings and rustfmt issues for CI compliance

Fix all clippy lints (collapsible if, clone on Copy, needless borrow,
redundant bindings, unused params) and apply rustfmt across the codebase.
Update test mocks to match Uuid-based trait signatures.

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

src/interfaces/api/handlers/admin_handler.rs

@@ -73,7 +73,11 @@ async fn admin_guard(state: &AppState, headers: &HeaderMap) -> Result<(Uuid, Str
         ));
     }
 
-    Ok((Uuid::parse_str(&claims.sub).map_err(|_| AppError::internal_error("Invalid user ID in token"))?, claims.role))
+    Ok((
+        Uuid::parse_str(&claims.sub)
+            .map_err(|_| AppError::internal_error("Invalid user ID in token"))?,
+        claims.role,
+    ))
 }
 
 /// GET /api/admin/settings/oidc — get OIDC settings for the admin panel