fix(android): bump versionName to 0.4.2 to match app.json; add ownership context

versionName in android/app/build.gradle was stale at 0.4.1 while app.json /
package.json declare 0.4.2, so CI-built APKs reported the wrong version string.
Align it. Also adds context.md (goal/design/plan/progress) and ignores the
generated index.android.bundle artifact.

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

.gitignore

@@ -13,3 +13,10 @@ ios/Pods/
 keystores/
 __pycache__/
 *.pyc
+
+# @generated expo-cli sync-2b81b286409207a5da26e14c78851eb30d8ccbdb
+# The following patterns were generated by expo-cli
+
+expo-env.d.ts
+# @end expo-cli
+android/app/src/main/assets/index.android.bundle