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-auth-ui/src/components/AuthGateModal.svelte

@@ -203,16 +203,21 @@
 <svelte:window onkeydown={handleKeydown} />
 
 {#if visible}
-	<!-- svelte-ignore a11y_click_events_have_key_events a11y_no_static_element_interactions -->
 	<div
 		class="fixed inset-0 z-50 flex items-center justify-center bg-black/50 backdrop-blur-sm p-4"
 		onclick={handleBackdropClick}
+		onkeydown={(e) => {
+			if (e.key === 'Escape') handleBackdropClick();
+		}}
+		role="presentation"
+		tabindex="-1"
 	>
 		<div
 			class="bg-card border-border relative mx-4 w-full max-w-md rounded-xl border p-6 shadow-2xl"
 			role="dialog"
 			aria-modal="true"
 			aria-labelledby="auth-gate-title"
+			tabindex="-1"
 			onclick={(e) => e.stopPropagation()}
 			use:trapFocus
 		>
@@ -230,7 +235,8 @@
 			<div
 				class="bg-primary/10 mx-auto mb-4 flex h-16 w-16 items-center justify-center rounded-full"
 			>
-				<svelte:component this={ActionIcon()} size={32} class="text-primary" />
+				{@const Icon = ActionIcon()}
+				<Icon size={32} class="text-primary" />
 			</div>
 
 			<!-- Title -->

packages/shared-auth-ui/src/components/GuestWelcomeModal.svelte

@@ -238,10 +238,12 @@
 
 {#if visible && appInfo}
 	<!-- Modal Backdrop -->
-	<!-- svelte-ignore a11y_no_noninteractive_element_interactions -->
 	<div
 		class="modal-backdrop"
 		onclick={handleBackdropClick}
+		onkeydown={(e) => {
+			if (e.key === 'Escape') handleBackdropClick();
+		}}
 		role="dialog"
 		aria-modal="true"
 		aria-labelledby="welcome-title"

packages/shared-auth-ui/src/pages/LoginPage.svelte

@@ -172,8 +172,8 @@
 	let rememberMe = $state(false);
 	let showSuccess = $state(false);
 	let shakeError = $state(false);
-	let emailInput: HTMLInputElement;
-	let passwordInput: HTMLInputElement;
+	let emailInput = $state<HTMLInputElement | undefined>(undefined);
+	let passwordInput = $state<HTMLInputElement | undefined>(undefined);
 	let successAnnouncement = $state('');
 	let showVerifiedBanner = $state(verified);
 	let showEmailNotVerified = $state(false);