runanywhere_genie: tolerate missing private binary at build time

The Genie engine is a closed-source private backend. When its release
asset isn't reachable (no network, release not yet published,
auth-gated distribution), the Flutter plugin's downloadNativeLibs
gradle task was hard-failing the build via ant.get throwing.

Wrap the download in try/catch so the plugin always builds. Runtime
absence is already handled: GeniePlugin.kt wraps System.loadLibrary
in try/catch and logs a warning; Dart bindings resolve
rac_backend_genie_register via the commons FFI and skip registration
when symbols aren't present.

Public repo now compiles cleanly without the Genie binary; consumers
who install the engine (either via testLocal=true local .so files or
via the published GitHub release) pick up NPU inference automatically.

Author: sanchitmonga22

sdk/runanywhere-flutter/packages/runanywhere_genie/android/build.gradle

@@ -103,10 +103,21 @@ task downloadNativeLibs {
 
             println "Downloading from: ${downloadUrl}"
 
-            // Download the zip file
-            ant.get(src: downloadUrl, dest: zipFile)
-
-            println "✅ Downloaded successfully"
+            // The Genie engine is a closed-source private backend. If the
+            // release asset isn't reachable (no network, release not yet
+            // published, auth-gated distribution), we must NOT fail the build —
+            // the Flutter plugin's GeniePlugin.kt wraps System.loadLibrary in
+            // try/catch, so absence is handled gracefully at runtime. Public
+            // builds that don't need Genie can proceed with empty jniLibs.
+            try {
+                ant.get(src: downloadUrl, dest: zipFile)
+                println "✅ Downloaded successfully"
+            } catch (Exception e) {
+                println "⚠️  Could not download RABackendGenie native libraries: ${e.message}"
+                println "⚠️  Continuing without Genie binaries — loadLibrary will fail gracefully at runtime."
+                println "⚠️  To build with the engine, either host the release at ${downloadUrl} or set testLocal=true with local .so files."
+                return
+            }
 
             // Extract to temp directory first
             def tempDir = file("${buildDir}/genie-temp")