chore(android): ignore local builds and signing material

.gitignore

@@ -11,6 +11,11 @@
 **/.vite/
 **/coverage/
 
+# Android / Gradle local state
+android-app/.gradle/
+android-app/**/build/
+android-app/local.properties
+
 # Backups / exports
 *.zip
 *.tar.gz
@@ -38,6 +43,8 @@ Thumbs.db
 *.key
 *.p12
 *.pfx
+*.jks
+*.keystore
 id_rsa
 id_ed25519
 *_github