known-good mac build before merging upstream 0.4.0

68 commits of mac work on top of upstream 0.3.2. app builds, runs, and the
dmg at release mac-v0.3.2 came from this tree. rollback point if the 0.4.0
merge goes wrong: git reset --hard checkpoint-pre-0.4.0

fix(player): quality menu only offers tiers the video actually has

when the companion tops out below the cap, rows above its real height
disappear instead of presenting choices that silently fail, and the
check marks what is actually playing rather than the unreachable cap.
the tops-out footer stays.

known good mac build: fullscreen player, synced lyrics with auto alig…

…n, playlist fix, search history, soft panel melt. roll back here if anything breaks.

chore: bump version to 0.2.1

Hotfix release for the 0.2.0 session-expiry bug. Adds the What's New
entry that explains the disappearing library / Premium status and that
this build fixes it.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

YTubic v0.2.0

feat: Ko-fi support link — README badge/section + About dialog button

Also aligns the About dialog blurb with the new "fast, responsive"
tagline.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>