feat(shared/ui): add Input and Textarea components with label and error states

src/shared/ui/Input/Textarea.svelte

@@ -0,0 +1,38 @@
+<!--
+    Component: Textarea
+    Brutalist multi-line input. Same styling as Input but <textarea>.
+    Non-resizable by default (matches prototype).
+-->
+<script lang="ts">
+import { cn } from '$shared/lib/cn';
+import type { HTMLTextareaAttributes } from 'svelte/elements';
+
+interface Props extends HTMLTextareaAttributes {
+    label?: string;
+    error?: string;
+    rows?: number;
+    class?: string;
+}
+
+let { label, error, rows = 4, class: className, ...rest }: Props = $props();
+
+const textareaClasses = $derived(cn(
+    'brutal-border bg-white px-4 py-3 text-carbon-black w-full resize-none',
+    'focus:outline-none focus:ring-2 focus:ring-burnt-oxide focus:ring-offset-2 focus:ring-offset-ochre-clay',
+    'transition-all duration-150',
+    'disabled:opacity-50 disabled:cursor-not-allowed',
+    className,
+));
+</script>
+
+<div class="flex flex-col gap-2">
+    {#if label}
+        <label class="text-carbon-black">{label}</label>
+    {/if}
+
+    <textarea {rows} class={textareaClasses} {...rest}></textarea>
+
+    {#if error}
+        <span class="text-sm text-burnt-oxide">{error}</span>
+    {/if}
+</div>