fix(ci): handle missing local.properties in CI environment

- Check if local.properties exists before reading
- Fallback to FLUTTER_ROOT environment variable
- Add FLUTTER_ROOT to CI variables
- Set default Flutter path to /opt/flutter for CI
- Fixes: 'local.properties (No such file or directory)' error

android/settings.gradle.kts

@@ -1,9 +1,17 @@
 pluginManagement {
     val flutterSdkPath = run {
         val properties = java.util.Properties()
-        file("local.properties").inputStream().use { properties.load(it) }
+        val localPropertiesFile = file("local.properties")
+        if (localPropertiesFile.exists()) {
+            localPropertiesFile.inputStream().use { properties.load(it) }
+        }
+        
+        // Try to get from local.properties first, then from environment variable
         val flutterSdkPath = properties.getProperty("flutter.sdk")
-        require(flutterSdkPath != null) { "flutter.sdk not set in local.properties" }
+            ?: System.getenv("FLUTTER_ROOT")
+            ?: System.getenv("FLUTTER_SDK")
+            ?: "/opt/flutter" // Default path in CI
+        
         flutterSdkPath
     }