feat: CS2 format support, player tracking fixes, and homepage enhancements

- Add dynamic MR12/MR15 halftime calculation to RoundTimeline component
- Fix TrackPlayerModal API signature (remove shareCode, change isOpen to open binding)
- Update Player types for string IDs and add ban fields (vac_count, vac_date, game_ban_count, game_ban_date)
- Add target/rel props to Button component for external links
- Enhance homepage with processing matches indicator
- Update preferences store for string player IDs
- Document Phase 5 progress and TypeScript fixes in TODO.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/lib/components/ui/Button.svelte

@@ -9,6 +9,8 @@
 		disabled?: boolean;
 		class?: string;
 		onclick?: () => void;
+		target?: string;
+		rel?: string;
 		children: Snippet;
 	}
 
@@ -20,6 +22,8 @@
 		disabled = false,
 		class: className = '',
 		onclick,
+		target,
+		rel,
 		children
 	}: Props = $props();
 
@@ -46,7 +50,7 @@
 </script>
 
 {#if href}
-	<a {href} class={classes} aria-disabled={disabled}>
+	<a {href} {target} {rel} class={classes} aria-disabled={disabled}>
 		{@render children()}
 	</a>
 {:else}