feat: Play Store and F-Droid dual release support

[najuna-brian]

Description

Enables Google Play and F-Droid from the same FOSS codebase. Builds on #647 (merged): per-ABI APK naming fix after #646.

This PR does not change the F-Droid metadata or build path (abiFilters, prebuild sed, init steps). It aligns CI and Gradle with that recipe and adds Play Store AAB output.

Changes

CI / GitHub Actions

• Run patch:android-foss and generate before release builds (same as F-Droid metadata init)
• Build bundleRelease for signed Play Store AABs
• Upload AAB as a workflow artifact; attach AAB + split APKs to GitHub Releases

Android build (build.gradle)

• Align per-ABI versionCode with F-Droid metadata (2–5 when base is 2) instead of the 100× formula
• Play AAB uses defaultConfig.versionCode; split APKs use base + ABI offset

Docs

• formulus/android/ANDROID_RELEASE.md: release prep, Play AAB flow, F-Droid flow, version codes

F-Droid impact

No fdroiddata changes in this PR. Existing metadata remains valid.

Test plan

• PR CI: Formulus Android & Formplayer Assets passes (debug APK on PR)
• After merge to dev: release job succeeds; AAB artifact present
• Optional: GitHub pre-release → AAB attached to release
• F-Droid: no metadata changes required

Post-merge

1. Merge to dev
2. Tag + GitHub pre-release (optional) → download AAB from Release or Actions artifacts
3. Upload AAB to Play Console (signed via repo secrets)
4. F-Droid: continue via separate fdroiddata MR

Related

• feat: enable per-ABI APK splits for F-Droid #646 — per-ABI release splits
• fix: unique APK filename per ABI split #647 — unique APK filename per ABI split (merged)

---

[r0ssing]

Looks good!