fix: revert gradle namespaces, add release Firebase config

Reverted gradle namespace changes (io.pezkuwichain.wallet -> io.novafoundation.nova)
because they break R class references in Kotlin code.

Internal namespaces are NOT user-visible, so this is acceptable for minimum rebrand.
User-visible elements are all properly branded as Pezkuwi.

Added google-services.json for release variant.

feature-proxy-api/build.gradle

@@ -1,6 +1,6 @@
 
 android {
-    namespace 'io.pezkuwichain.wallet.feature_proxy_api'
+    namespace 'io.novafoundation.nova.feature_proxy_api'
 }
 
 dependencies {