feat(gyeol): Q3Step — 멀티 체크 9개 + 기타 자유 입력

validation: 최소 1개 체크 또는 기타 입력 있어야 다음 활성.
체크박스 패턴 + 활성 시 보라 + 흰 체크마크.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/gyeol/components/Q3Step.tsx

@@ -0,0 +1,89 @@
+'use client';
+
+import { useState } from 'react';
+import { TOOLS_OPTIONS } from '@/lib/survey/questions';
+import type { SurveyResponse } from '@/lib/survey/types';
+import QuestionLayout from './QuestionLayout';
+
+interface Props {
+  initial: Partial<SurveyResponse>;
+  onPrev: () => void;
+  onNext: (partial: Partial<SurveyResponse>) => void;
+}
+
+export default function Q3Step({ initial, onPrev, onNext }: Props) {
+  const [selected, setSelected] = useState<string[]>(initial.tools_used ?? []);
+  const [other, setOther] = useState(initial.tools_other ?? '');
+
+  function toggle(option: string) {
+    setSelected((prev) =>
+      prev.includes(option) ? prev.filter((x) => x !== option) : [...prev, option]
+    );
+  }
+
+  // validation: 최소 1개 체크 또는 기타 입력 있음
+  const valid = selected.length > 0 || other.trim().length > 0;
+
+  return (
+    <QuestionLayout
+      step="q3"
+      onPrev={onPrev}
+      onNext={() =>
+        onNext({
+          tools_used: selected,
+          tools_other: other.trim() || undefined,
+        })
+      }
+      nextDisabled={!valid}
+    >
+      <div className="space-y-2">
+        {TOOLS_OPTIONS.map((option) => {
+          const checked = selected.includes(option);
+          return (
+            <label
+              key={option}
+              className={`flex items-center gap-3 px-4 py-3 rounded-xl border cursor-pointer transition ${
+                checked
+                  ? 'border-violet-400 bg-violet-400/10'
+                  : 'border-white/15 bg-white/[0.02] hover:border-white/30'
+              }`}
+            >
+              <input
+                type="checkbox"
+                checked={checked}
+                onChange={() => toggle(option)}
+                className="sr-only"
+              />
+              <span
+                className={`w-4 h-4 rounded border-2 flex items-center justify-center flex-shrink-0 ${
+                  checked ? 'border-violet-400 bg-violet-400' : 'border-white/30'
+                }`}
+              >
+                {checked && (
+                  <svg className="w-3 h-3 text-black" fill="none" stroke="currentColor" viewBox="0 0 24 24" strokeWidth={3}>
+                    <path strokeLinecap="round" strokeLinejoin="round" d="M5 13l4 4L19 7" />
+                  </svg>
+                )}
+              </span>
+              <span className="text-sm text-white">{option}</span>
+            </label>
+          );
+        })}
+
+        <div className="pt-2">
+          <label className="block text-xs text-white/60 mb-2 font-mono tracking-widest uppercase">
+            기타 (직접 입력)
+          </label>
+          <input
+            type="text"
+            value={other}
+            onChange={(e) => setOther(e.target.value)}
+            placeholder="예: 명상, 운동"
+            maxLength={100}
+            className="w-full px-4 py-3 rounded-xl bg-white/[0.04] border border-white/15 text-white placeholder:text-white/30 focus:border-white/40 focus:outline-none"
+          />
+        </div>
+      </div>
+    </QuestionLayout>
+  );
+}