release(4.2.0): bump versionName to 4.2.0 and versionCode to 218

[WRRicht3r]

Summary

Prepare stable release 4.2.0:

• Bump versionName to 4.2.0 and versionCode to next
• Add release docs: 4.2.0-beta.1, 4.2.0 (stable), and PROCESS
• Add Play release notes (beta + production)

Related Issue

Relates to #1235 #1236 #1239 #1240

Type of Change

• feat (new feature)
• fix (bug fix)
• refactor (no functional change)
• chore/build (tooling, CI, deps)
• docs (README/AGENTS, comments)

Screenshots / Videos

N/A — docs + version bump only.

Test Plan

Commands run locally:
./gradlew detektAll
./gradlew runTest
./gradlew :app:lint
Additional checks and scenarios covered:

• printPolkadotSdkAlignment
• postMergeVerify (fast-fail order)
• assembleRelease sanity (for artifact)

Risks & Rollout

Low (docs + version bump). Proceed with staged rollout per docs/releases/4.2.0.md.

Checklist

• Linked an issue and added a clear description
• Updated docs (release notes/process)
• Ran detektAll, runTest, and :app:lint locally (or CI)
• No secrets or local.properties committed

[takemiyamakoto]

@codex review deez

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Nice work!

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