Expose the grid columns picker in SubscriptionsView and ManageChannelsView
inline sheets, and track viewWidth in ChannelView's tvOS GeometryReaders so
the shared ViewOptionsSheet can compute a meaningful column range.
Replace the tvOS Subscriptions header (All Channels link + View Options
button) with a left-column channels sidebar that filters the feed in
place, and move view options into a button at the top of the sidebar.
Drops the channel strip size picker from the tvOS options sheet since
the strip does not apply there, and mirrors the ContinueWatchingView
focus pattern so initial focus and post-filter focus land on the first
video row.
Move the channel-link button and View Options into a top safe-area inset
on tvOS so they are reachable with the remote, mirroring the Continue
Watching pattern. Wrap chrome and content in focus sections with a
default-focus namespace so initial focus lands on the first video. Hide
the duplicate in-content section header on tvOS, and add
scrollClipDisabled to VideoListContainer so focus scaling on rows is
not clipped at the scroll edges.
Renames YatteeServerCredentialsManager → BasicAuthCredentialsManager so the
same Keychain-backed username/password storage can be reused for any instance
type that sits behind a reverse proxy requiring HTTP Basic Auth. Adds a
one-time migration that moves existing items from the legacy
'com.yattee.yatteeserver' Keychain service to 'com.yattee.basicauth',
preserving the iCloud-sync attribute. No behavior change for end users.
On tvOS, ContentUnavailableView inside a Group doesn't expand to fill
available space — it sizes to content and aligns top-leading. Add
.frame(maxWidth: .infinity, maxHeight: .infinity) to all instances
so they center correctly in their parent containers.
