fix(watchlist): refine layout density, clipping, and scroll animation

[Himanth-reddy]

Summary

This PR polishes the Watchlist / Library screen UI and D-pad navigation across Android TV and mobile:

• Dedicated My Watchlist Module: Modularized MyWatchlistView so My Watchlist consistently presents horizontal Movies and Series section rows rather than collapsing into a vertical grid when only a single media type exists.
• Fix Series Row Clipping: Added 8.dp top / 12.dp bottom padding to LazyRow and 120.dp bottom clearance to LazyColumn to prevent focused card scaling and elevation shadows from being clipped on TV.
• Clean Single-Type Grid: Removed redundant Movies 60 / Series 60 section header in single-type catalog/server grids so cards start directly below the list selector.
• Row-Aligned Grid Scrolling: Fixed jumping/snapping when navigating up or down from columns > 0 by aligning animateScrollToItem to the row start index.
• Symmetric Scroll Speed: Added smooth scrolling helpers (animateSmoothGridScroll and animateSmoothListScroll) using exact delta measurement and uniform easing in both directions.
• Source Selection Reset: Reset watchlistColumnState.scrollToItem(0) when switching sources alongside the existing gridState reset.
• Manage Lists Button: Commented out the unlinked ManageListsGhostButton with a clear TODO until list management workflows are ready.

Testing

• Verified on Television_1080p(AVD) emulator.
• Passed all unit tests: ./gradlew testPlayDebugUnitTest --tests "*Watchlist*".

[ProdigyV21]

Got screenshots of how it looks?