refactor: clean up styles and improve layout in dashboard and edit channel components

- Removed unnecessary class names for buttons in ChannelCard and DashboardPage components.
- Updated layout styles in RootLayout to apply dark mode by default.
- Refactored edit-channel-sheet to streamline block editor and filter editor components.
- Adjusted duration input fields to reflect minutes instead of seconds in AlgorithmicFilterEditor.
- Enhanced the structure of the EditChannelSheet for better readability and maintainability.

k-tv-frontend/app/(main)/dashboard/components/channel-card.tsx

@@ -168,7 +168,6 @@ export function ChannelCard({
           size="icon-sm"
           onClick={onViewSchedule}
           title="View schedule"
-          className="border-zinc-700 text-zinc-400 hover:text-zinc-100"
         >
           <CalendarDays className="size-3.5" />
         </Button>
@@ -176,7 +175,6 @@ export function ChannelCard({
           size="icon-sm"
           asChild
           title="Watch on TV"
-          className="border-zinc-700 text-zinc-400 hover:text-zinc-100"
         >
           <Link href={`/tv?channel=${channel.id}`}>
             <Tv2 className="size-3.5" />