This commit updates the app version to 0.2.0-beta, updates the `CHANGELOG.md`, and correctly implements the in-app changelog.

Changes include:
- Updated `APP_VERSION_NAME` to `0.2.0-beta` and `APP_VERSION_CODE` to `2` in `gradle.properties`.
- Added a new entry to `CHANGELOG.md` for version `0.2.0-beta`, correcting previous inaccuracies.
- Refactored `ChangelogBottomSheet.kt` to display a structured, data-driven changelog.
- Added a Floating Action Button to `ChangelogBottomSheet.kt` that links to the full changelog on GitHub.
- Reverted incorrect changes from `AboutScreen.kt`.

This commit addresses UI layout issues where content was being obscured by other components.

1.  **About Screen:** The bottom padding of the `LazyColumn` has been increased to account for the `MiniPlayerHeight`. This prevents the last items in the list from being hidden behind the mini-player.
2.  **Changelog Bottom Sheet:**
    - Padding has been added to the bottom of the `LazyColumn` to ensure the final changelog entry is fully visible and not cut off by the sheet's edge.
    - The URL for the changelog has been corrected to point to the `master` branch, ensuring the link is valid.