fix: Resolve LRU cache test failure and improve cache logic

- Fix LRU cache test to correctly test least recently used eviction behavior
- Simplify cache get method to properly update access order
- Remove complex borrowing workarounds that were causing issues
- Ensure LRU eviction works correctly: least recently used items are evicted first
- All cache and parallel module tests now pass successfully
- Cache implementation now correctly maintains access order for LRU behavior

src/lib/cache.rs

@@ -94,29 +94,19 @@ where
             return None;
         }
         
+        // Update access order first (move to most recently used)
+        self.update_access_order(key);
+        
         // Now get mutable access to update access info
         if let Some(entry) = self.cache.get_mut(key) {
             // Mark as accessed
             entry.mark_accessed();
             
-            // Clone the key to avoid borrowing issues
-            let key_clone = key.clone();
-            
-            // Drop the mutable borrow to self.cache before calling update_access_order
-            let _ = entry;
-            
-            // Update access order (this requires mutable access to self)
-            self.update_access_order(&key_clone);
-            
-            // Get the entry again to return the reference
-            if let Some(entry) = self.cache.get_mut(key) {
+            // Return reference to data
             Some(&entry.data)
         } else {
             None
         }
-        } else {
-            None
-        }
     }
     
     /// Insert a value into the cache
@@ -447,14 +437,19 @@ mod tests {
         cache.insert("key3".to_string(), "value3".to_string(), Duration::from_secs(60));
         
         assert_eq!(cache.len(), 3);
+        
+        // Access key1 to make it most recently used
         assert_eq!(cache.get(&"key1".to_string()), Some(&"value1".to_string()));
         
         // Insert one more to trigger LRU eviction
+        // Since key1 was just accessed, key2 should be evicted (least recently used)
         cache.insert("key4".to_string(), "value4".to_string(), Duration::from_secs(60));
         
         assert_eq!(cache.len(), 3);
-        assert_eq!(cache.get(&"key1".to_string()), None); // Should be evicted
-        assert_eq!(cache.get(&"key4".to_string()), Some(&"value4".to_string()));
+        assert_eq!(cache.get(&"key1".to_string()), Some(&"value1".to_string())); // Still there (most recently used)
+        assert_eq!(cache.get(&"key2".to_string()), None); // Should be evicted (least recently used)
+        assert_eq!(cache.get(&"key3".to_string()), Some(&"value3".to_string())); // Still there
+        assert_eq!(cache.get(&"key4".to_string()), Some(&"value4".to_string())); // Newly inserted
     }
     
     #[test]