feat: add base activity architecture

- Create BaseActivity for common functionality
- Implement lifecycle management
- Add common UI helpers
- Reduce code duplication across activities

Author: Natifishman

app/src/main/java/com/example/partymaker/ui/base/BaseActivity.java

@@ -0,0 +1,71 @@
+package com.example.partymaker.ui.base;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.util.Log;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.lifecycle.ViewModelStore;
+import com.example.partymaker.utils.infrastructure.system.MemoryManager;
+
+/**
+ * Base activity with memory management integration.
+ * All major activities should extend this class for proper memory handling.
+ */
+public abstract class BaseActivity extends AppCompatActivity {
+    private static final String TAG = "BaseActivity";
+    private String activityKey;
+    
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        activityKey = getClass().getSimpleName() + "_" + System.currentTimeMillis();
+        MemoryManager.getInstance().registerObject(activityKey, this);
+        MemoryManager.getInstance().logMemoryStats();
+    }
+    
+    @Override
+    protected void onStart() {
+        super.onStart();
+        MemoryManager.getInstance().clearUnusedResources();
+    }
+    
+    @Override
+    public void onTrimMemory(int level) {
+        super.onTrimMemory(level);
+        switch (level) {
+            case TRIM_MEMORY_RUNNING_MODERATE:
+            case TRIM_MEMORY_RUNNING_LOW:
+                MemoryManager.getInstance().clearImageCache();
+                break;
+            case TRIM_MEMORY_RUNNING_CRITICAL:
+                MemoryManager.getInstance().emergencyCleanup();
+                break;
+            case android.content.ComponentCallbacks2.TRIM_MEMORY_BACKGROUND:
+                break;
+            case android.content.ComponentCallbacks2.TRIM_MEMORY_COMPLETE:
+                break;
+            case android.content.ComponentCallbacks2.TRIM_MEMORY_MODERATE:
+                break;
+            case android.content.ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN:
+                break;
+        }
+    }
+    
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        MemoryManager.getInstance().unregisterObject(activityKey);
+        
+        // Clear ViewModels
+        getViewModelStore().clear();
+        
+        // Clear any remaining references
+        clearActivityReferences();
+    }
+    
+    /**
+     * Override this method to clear activity-specific references
+     * to prevent memory leaks
+     */
+    protected abstract void clearActivityReferences();
+}