Chatovo v1.3.8

chore(release): 1.3.8

Declare the Android Gradle wiring in [package.metadata.cargo-android] instead
of patching the generated build files: the google-services plugin, its
classpath and the RuStore appupdate dependency now come from Cargo.toml, which
the Tauri CLI applies while generating gen/android. The setup scripts keep only
what has no hook there — the VK maven repositories, MainActivity, the proguard
rules and google-services.json.

Add a targets input to the release workflow so a manual run can rebuild one
platform, and keep the release a draft unless something actually built.

Document the RuStore signing flow that the console needs: the legacy PKCS12
flag pepk requires, the pepk/keytool commands, and the fact that the first
version has to be published by hand before the API can create drafts.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>