feat: add BaseActivity for edge-to-edge support

This commit introduces `BaseActivity`, an abstract class extending `AppCompatActivity`. It implements edge-to-edge display logic using `WindowCompat` and `ViewCompat.setOnApplyWindowInsetsListener` to handle system bar insets automatically for all extending activities.

Author: eby-dev

app/src/main/java/com/ahmadabuhasan/qrbarcode/utils/BaseActivity.kt

@@ -0,0 +1,36 @@
+package com.ahmadabuhasan.qrbarcode.utils
+
+import android.os.Bundle
+import android.view.View
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.view.ViewCompat
+import androidx.core.view.WindowCompat
+import androidx.core.view.WindowInsetsCompat
+
+abstract class BaseActivity : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        WindowCompat.setDecorFitsSystemWindows(window, false)
+        applyEdgeToEdge()
+        super.onCreate(savedInstanceState)
+    }
+
+    private fun applyEdgeToEdge() {
+        val content = findViewById<View>(android.R.id.content)
+
+        ViewCompat.setOnApplyWindowInsetsListener(content) { view, insets ->
+            val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
+
+            view.setPadding(
+                view.paddingLeft,
+                systemBars.top,
+                view.paddingRight,
+                systemBars.bottom
+            )
+
+            insets
+        }
+
+    }
+
+}