feat: replace pretzel emoji with favicon across the app

Use the new favicon SVG in the header, login, setup, empty state,
and error pages. Keep the pretzel emoji in the footer tagline.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/lib/components/Layout/Header.svelte

@@ -28,6 +28,7 @@
 		</button>
 
 		<div class="flex items-center gap-2">
+			<img src="/favicon.svg" alt="" class="h-8 w-8" />
 			<h1 class="font-['Press_Start_2P'] text-lg text-[var(--primary)]">Crumbs</h1>
 		</div>
 

src/routes/(app)/+page.svelte

@@ -77,7 +77,7 @@
 
 {#if $notesLoaded && $pinnedNotes.length === 0 && $unpinnedNotes.length === 0}
 	<div class="flex flex-col items-center justify-center py-20 text-[var(--text-muted)]">
-		<span class="mb-4 text-7xl">🥨</span>
+		<img src="/favicon.svg" alt="" class="mb-4 h-18 w-18" />
 		<p class="font-['Press_Start_2P'] text-xs">
 			{#if $currentFilter === 'trashed'}
 				No crumbs in trash

src/routes/(auth)/login/+page.svelte

@@ -35,7 +35,7 @@
 
 <div class="w-full max-w-sm rounded-sm border border-[var(--border)] bg-[var(--bg-surface)] p-8 shadow-[var(--card-shadow)]">
 	<div class="mb-6 text-center">
-		<span class="text-5xl">🥨</span>
+		<img src="/favicon.svg" alt="Crumbs" class="mx-auto h-12 w-12" />
 		<h1 class="font-['Press_Start_2P'] text-xl text-[var(--primary)]">Crumbs</h1>
 		<p class="mt-2 text-sm text-[var(--text-muted)]">Enter your password to continue</p>
 	</div>

src/routes/(auth)/setup/+page.svelte

@@ -47,7 +47,7 @@
 
 <div class="w-full max-w-sm rounded-sm border border-[var(--border)] bg-[var(--bg-surface)] p-8 shadow-[var(--card-shadow)]">
 	<div class="mb-6 text-center">
-		<span class="text-5xl">🥨</span>
+		<img src="/favicon.svg" alt="Crumbs" class="mx-auto h-12 w-12" />
 		<h1 class="font-['Press_Start_2P'] text-xl text-[var(--primary)]">Welcome to Crumbs</h1>
 		<p class="mt-2 text-sm text-[var(--text-muted)]">Set up your password to get started</p>
 	</div>

src/routes/+error.svelte

@@ -8,7 +8,7 @@
 
 <div class="flex min-h-screen items-center justify-center bg-[var(--bg-base)]">
 	<div class="w-full max-w-sm rounded-sm border border-[var(--border)] bg-[var(--bg-surface)] p-8 text-center">
-		<span class="text-5xl">🥨</span>
+		<img src="/favicon.svg" alt="Crumbs" class="mx-auto h-12 w-12" />
 		<h1 class="mt-4 font-['Press_Start_2P'] text-xl text-[var(--primary)]">
 			{page.status}
 		</h1>