fix: resolve runtime errors and missing routes

- Fix $effect orphan error: move $effect calls from store constructors
  to initEffects() methods called from component context
- Fix icon rendering: create DynamicIcon component to render Lucide icons
  from name strings instead of displaying raw text
- Add /boards/new route for board creation
- Fix seed emails (admin@launcher.local / user@launcher.local) to pass
  Zod email validation

src/lib/components/section/SectionHeader.svelte

@@ -1,4 +1,6 @@
 <script lang="ts">
+	import DynamicIcon from '$lib/components/ui/DynamicIcon.svelte';
+
 	interface Props {
 		title: string;
 		icon: string | null;
@@ -29,7 +31,7 @@
 	</svg>
 
 	{#if icon}
-		<span class="text-base">{icon}</span>
+		<DynamicIcon name={icon} size={18} />
 	{/if}
 
 	<span class="font-medium text-foreground">{title}</span>