fix: resolve all 40 Svelte dev warnings for clean startup

- Add $state() to 4 reactive variables (guestMode, emailInput, passwordInput, searchInputElement)
- Replace 3 deprecated <svelte:component> with direct component references
- Fix 8 a11y issues: add ARIA roles, tabindex, keyboard handlers to click-handler divs
- Remove 22 unused CSS selectors across 8 shared-ui components

Zero warnings on dev startup.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/shared-ui/src/navigation/PillTimeRangeSelector.svelte

@@ -273,12 +273,6 @@
 			0 4px 6px -2px hsl(var(--color-foreground) / 0.05);
 	}
 
-	.pill-icon {
-		width: 1rem;
-		height: 1rem;
-		flex-shrink: 0;
-	}
-
 	.pill-label {
 		font-size: 0.8125rem;
 	}
@@ -316,17 +310,6 @@
 		color: hsl(var(--color-primary));
 	}
 
-	.chevron-icon {
-		width: 0.75rem;
-		height: 0.75rem;
-		transition: transform 0.2s;
-		margin-left: 0.125rem;
-	}
-
-	.chevron-icon.rotated {
-		transform: rotate(180deg);
-	}
-
 	.backdrop {
 		position: fixed;
 		inset: 0;