chore(android): rename the RuStore signing secrets ANDROID_* -> ANDROID_RUSTORE_*

The signing key is store-specific: RuStore self-signs (the cert is the app cert), while Google Play re-signs via Play App Signing (the uploaded key is only the upload key). Keep a separate key per store and name the secrets accordingly. Only the Gitea secret names change; build.gradle keeps the store-agnostic env contract (ANDROID_KEYSTORE_*), so the same build serves a future Google key from its own workflow. New names: ANDROID_RUSTORE_KEYSTORE_BASE64 / _KEYSTORE_PASSWORD / _KEY_ALIAS / _KEY_PASSWORD.

deploy/README.md

@@ -257,8 +257,8 @@ web/prod rollout — a signed APK uploaded to RuStore by hand. The build/release
   the SDK is missing or unreadable.
 - **Release keystore** (create once, **back up off-host** — losing it means the app can never be updated):
   `keytool -genkeypair -v -keystore erudit-release.jks -alias erudit -keyalg RSA -keysize 4096 -validity 10000`,
-  then set the Gitea **secrets** `ANDROID_KEYSTORE_BASE64` (`base64 -w0 erudit-release.jks`),
-  `ANDROID_KEYSTORE_PASSWORD`, `ANDROID_KEY_ALIAS`, `ANDROID_KEY_PASSWORD`. Set the `ANDROID_RUSTORE_URL`
+  then set the Gitea **secrets** `ANDROID_RUSTORE_KEYSTORE_BASE64` (`base64 -w0 erudit-release.jks`),
+  `ANDROID_RUSTORE_KEYSTORE_PASSWORD`, `ANDROID_RUSTORE_KEY_ALIAS`, `ANDROID_RUSTORE_KEY_PASSWORD`. Set the `ANDROID_RUSTORE_URL`
   variable to the store listing once published (empty until then — the in-app update button no-ops).
 - **Wire-break discipline:** the prod deploy that ships an incompatible wire change **also** bumps
   `GATEWAY_MIN_CLIENT_VERSION` to that release (see Optional variables), so an old installed APK is turned