feat: 입력 프리미티브 (TextInput / Textarea / Select) + tsconfig 보정

UX/UI 개편 Phase A-6.

신규 컴포넌트 (lib/components/ui/)
- TextInput.svelte: \$bindable value, label/error/hint, leading/trailing icon,
  \$props.id() 기반 SSR-safe 자동 id, aria-describedby 자동 연결.
- Textarea.svelte: TextInput과 동일 구조 + autoGrow 옵션
  (\$effect로 scrollHeight 동기화, maxRows 지원).
- Select.svelte: 네이티브 <select> 래퍼, ChevronDown 표시.
  options: { value, label, disabled? }[]

빌드 환경 보정
- frontend/tsconfig.json 신규: svelte-kit 자동 생성 .svelte-kit/tsconfig.json을
  extends. 이게 없으면 svelte-check가 \$lib path mapping과 .svelte.ts 모듈
  resolution을 못 잡아 "Cannot find module" 에러 발생. SvelteKit 표준 패턴.
  strict는 false로 시작 (기존 코드 implicit any 다수 — 점진적 정리 예정).
- Button/IconButton/EmptyState/TextInput의 icon prop 타입을 IconComponent(any)로
  완화. lucide-svelte v0.400은 legacy SvelteComponentTyped 기반이라 Svelte 5의
  Component<P, E, B> 시그니처와 호환 안 됨. v0.469+ 업그레이드 후 좁힐 예정.

svelte-check: 0 errors / 8 warnings (전부 기존 latent, 새 코드 무관)
build: 2.07s 무경고

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

frontend/src/lib/components/ui/Textarea.svelte

@@ -0,0 +1,105 @@
+<script lang="ts">
+  // 공용 textarea. TextInput과 같은 구조 + autoGrow 옵션.
+  interface Props {
+    value?: string;
+    label?: string;
+    error?: string;
+    hint?: string;
+    placeholder?: string;
+    id?: string;
+    name?: string;
+    rows?: number;
+    disabled?: boolean;
+    readonly?: boolean;
+    required?: boolean;
+    autoGrow?: boolean;
+    maxRows?: number;
+    class?: string;
+  }
+
+  let {
+    value = $bindable(''),
+    label,
+    error,
+    hint,
+    placeholder,
+    id: idProp,
+    name,
+    rows = 3,
+    disabled = false,
+    readonly = false,
+    required = false,
+    autoGrow = false,
+    maxRows,
+    class: className = '',
+    ...rest
+  }: Props = $props();
+
+  const autoId = $props.id();
+  let inputId = $derived(idProp ?? `textarea-${autoId}`);
+  let hintId = $derived(`${inputId}-hint`);
+  let errorId = $derived(`${inputId}-error`);
+  let describedBy = $derived(
+    [error ? errorId : null, hint && !error ? hintId : null].filter(Boolean).join(' ') || undefined
+  );
+
+  let textareaEl: HTMLTextAreaElement | undefined = $state();
+
+  // autoGrow: value 변경 시마다 height를 scrollHeight로 동기화
+  $effect(() => {
+    if (!autoGrow || !textareaEl) return;
+    // value를 reactivity 의존성으로 등록
+    void value;
+    textareaEl.style.height = 'auto';
+    let next = textareaEl.scrollHeight;
+    if (maxRows) {
+      const lineHeight = parseFloat(getComputedStyle(textareaEl).lineHeight) || 20;
+      const maxHeight = lineHeight * maxRows;
+      if (next > maxHeight) next = maxHeight;
+    }
+    textareaEl.style.height = next + 'px';
+  });
+
+  let textareaClass = $derived(
+    [
+      'w-full px-3 py-2 rounded-md text-sm bg-bg text-text placeholder:text-faint',
+      'border outline-none transition-colors',
+      error
+        ? 'border-error focus:border-error focus:ring-2 focus:ring-error/30'
+        : 'border-default focus:border-accent focus:ring-2 focus:ring-accent-ring',
+      'disabled:opacity-50 disabled:cursor-not-allowed',
+      autoGrow ? 'resize-none overflow-hidden' : 'resize-y',
+    ].join(' ')
+  );
+</script>
+
+<div class={'flex flex-col gap-1 ' + className}>
+  {#if label}
+    <label for={inputId} class="text-xs font-medium text-dim">
+      {label}
+      {#if required}<span class="text-error">*</span>{/if}
+    </label>
+  {/if}
+
+  <textarea
+    id={inputId}
+    bind:this={textareaEl}
+    bind:value
+    {name}
+    {rows}
+    {placeholder}
+    {disabled}
+    {readonly}
+    {required}
+    class={textareaClass}
+    aria-invalid={error ? 'true' : undefined}
+    aria-describedby={describedBy}
+    {...rest}
+  ></textarea>
+
+  {#if error}
+    <p id={errorId} class="text-xs text-error">{error}</p>
+  {:else if hint}
+    <p id={hintId} class="text-xs text-faint">{hint}</p>
+  {/if}
+</div>