chore(android): git-ignore keystore.properties + add example

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -38,6 +38,7 @@ captures/
 # Keystore files
 *.jks
 *.keystore
+keystore.properties
 
 # macOS
 .DS_Store

keystore.properties.example

@@ -0,0 +1,9 @@
+# Copy this file to "keystore.properties" (git-ignored) and fill in your real
+# values to enable a signed release build:  ./gradlew bundleRelease
+#
+# storeFile: ABSOLUTE path to your upload keystore (.jks). Keep the keystore and
+# this filled-in file OUT of version control (both are git-ignored).
+storeFile=/absolute/path/to/upload-keystore.jks
+storePassword=CHANGE_ME
+keyAlias=upload
+keyPassword=CHANGE_ME