Prepare the 0.23.0-beta.1 release (build 30)

[ultraelectronica]

Summary

Packages the 0.23.0-beta.1 pre-release: version bump, changelog, release notes, and the matching in-app What's New entry. No runtime behavior changes — this is the release-prep commit for the localization, widget, Replay, and audio-hardening work already on the branch.

Version

• Bumps pubspec.yaml from 0.22.1-beta.3+29 to 0.23.0-beta.1+30.
• Updates kAppVersion, kAppBuild, and the derived kAppVersionLabel in lib/core/constants/app_constants.dart in lockstep.
• Refreshes the current version code in docs/RELEASING.md.

Release notes

• Adds the 0.23.0-beta.1 (2026-10-19) section to CHANGELOG.md, grouped as Localization & Typography, Mini Player & Home Widgets, Display & Visualizer, Replay & Recap, USB & DSD Audio, Playback Reliability, Library/Network/Artwork, and Interface & Polish.
• Adds docs/RELEASE_0.23.0-beta.1.md with the release highlights, build/flavor guidance (GitHub full APK with All Files Access vs. Play play AAB without it, both sharing com.mossapps.flick), and Getting Started steps for language, mini player, the Replay widget, and Replay Studio.
• Adds the matching 0.23.0-beta.1 entry to lib/features/whats_new/data/changelog_data.dart so the What's New sheet surfaces on the first launch after updating (kAppVersion and the entry version agree).

Related issue

none

Checklist

• flutter analyze passes
• flutter test passes
• Rust changes: cargo test --manifest-path rust/Cargo.toml passes
• Built and ran the app if the change touches a playback path (flutter run --flavor full)
• Generated code regenerated and committed if bridge/drift/freezed models changed
• CHANGELOG.md updated for user-facing changes
• No secrets, keys, tokens, or machine-local files committed
• One change per PR; no unrelated reformatting in the same diff
• Hardware tested if the Rust audio engine or USB/DAC output changed