Publish Google Play drafts through Fastlane and release CI

[andre487]

Adds bundle exec fastlane android play_release to upload a signed release AAB and its matching native debug symbols to Google Play. Local uploads default to an internal-track draft, with explicit track/status overrides and API validation without committing a release.

The existing tag-triggered release workflow now builds and verifies artifacts, publishes the GitHub Release, then uploads an internal Google Play draft. Play upload failures fail the workflow while leaving the GitHub Release available. The standard SUPPLY_JSON_KEY_DATA environment variable carries the complete service-account JSON for both local runs and the release upload step, which receives the matching repository Actions secret. PR workflows receive no Play credentials.

The lane validates parameters, credential structure and input files before upload. Store listing metadata and artwork are skipped. English and Russian documentation covers account setup, local env usage and the automated release flow.

Validation:

• Ruby syntax and git diff --check passed.
• 20 integration smoke checks passed through the pinned Fastlane runner and action configuration with the network uploader replaced, covering defaults, overrides, input failures, credential parsing and secret-free errors.
• Release workflow YAML, tag trigger, step ordering and explicit internal/draft arguments verified; other workflows contain no Play secret references.
• Local release env was verified to load the supplied key with permissions 0600; the repository secret was configured and its existence verified without exposing its value.
• Native race tests and Android JVM/Compose tests, lint, debug/release builds and unsigned release verification passed before the credentials/workflow follow-ups; PR CI runs on each push.
• Real Google Play API validation passed with play_release track:internal release_status:draft validate_only:true: checksummed AAB versionCode 12000 and matching native symbols uploaded, internal-track edit validated successfully, no release committed. The release workflow itself was not triggered.

[github-actions]

APK artifacts

• Download debug APK — signed with the disposable Android debug key
• Download unsigned release APK — verified unsigned

Built from commit b8db1d45 by CI run #145.
Artifacts expire after 14 days. Neither APK uses the MegaProxy release key.