feat: Sheets 템플릿 가이드 보강(TDD)

- Code.gs에 @tool/@version 헤더, 필드 매핑 TODO, try/catch 에러 처리 추가
- README.txt에 Web App 배포/필드 매핑 가이드 추가
- 테스트 추가: sheets.template.enhance.test.ts
- 전체 테스트 그린 유지

lib/exporter/extras.ts

@@ -68,13 +68,25 @@ export function buildExtrasForPage(page: Page, overrides?: ExtrasOverrides): Rec
     const code = `/**
  * Google Apps Script Web App for form submissions
  * - Deploy as Web App and set URL as form action if needed.
+ * @tool: landing-builder
+ * @version: 1.0.0
  */
 function doPost(e){
-  // TODO: handle submission to Google Sheets
-  return ContentService.createTextOutput('OK')
+  try {
+    // TODO: map incoming fields to sheet columns
+    // Example:
+    // const payload = JSON.parse(e.postData.contents || '{}');
+    // const row = [payload.name, payload.email, new Date()];
+    // SpreadsheetApp.openById('YOUR_SHEET_ID').getSheetByName('Sheet1').appendRow(row);
+    return ContentService.createTextOutput('OK')
+  } catch (e) {
+    return ContentService
+      .createTextOutput('ERROR: ' + (e && (e as any).message ? (e as any).message : 'unknown'))
+      .setMimeType(ContentService.MimeType.TEXT)
+  }
 }
 `
-    const readme = `Google Sheets Apps Script Template\n\n1) Apps Script에서 새 프로젝트를 만들고 아래 Code.gs를 붙여넣으세요.\n2) 배포 > 웹 앱으로 배포 후 URL을 복사해 사용하세요.`
+    const readme = `Google Sheets Apps Script Template\n\n1) Apps Script에서 새 프로젝트를 만들고 아래 Code.gs를 붙여넣으세요.\n2) Deploy as Web App로 배포 후 URL을 복사해 사용하세요.\n3) Map fields to columns: 제출 payload의 필드를 시트 컬럼에 매핑하세요.`
     out['sheets/Code.gs'] = toBytes(code)
     out['sheets/README.txt'] = toBytes(readme)
   }

lib/exporter/sheets.template.enhance.test.ts

@@ -0,0 +1,46 @@
+import { describe, it, expect } from 'vitest'
+import { buildExtrasForPage } from '@/lib/exporter/extras'
+import type { Page } from '@/lib/schema/page'
+
+function td(b: Uint8Array){ return new TextDecoder().decode(b) }
+
+const basePage: Page = {
+  title: 'Test',
+  seo: { title: 'T', description: 'D' },
+  theme: { primaryColor: '#0ea5e9', fontFamily: 'Inter' },
+  analytics: { ga4MeasurementId: '', metaPixelId: '', customHeadHtml: '' },
+  sections: [],
+  form: {
+    fields: [],
+    actionUrl: '',
+    spamProtection: { honeypotFieldName: '_hp', minSubmitSeconds: 2 },
+  },
+  locale: 'en',
+}
+
+describe('Sheets template enhance', () => {
+  it('includes version/meta and mapping/error guide in Code.gs and README', () => {
+    const extras = buildExtrasForPage(basePage, { sheetsMode: 'include' })
+    const code = td(extras['sheets/Code.gs'])
+    const readme = td(extras['sheets/README.txt'])
+
+    // version/meta header
+    expect(code).toMatch(/@version:\s*\d+\.\d+\.\d+/)
+    expect(code).toMatch(/@tool:\s*landing-builder/i)
+
+    // field mapping and error handling guides
+    expect(code).toMatch(/TODO:\s*map incoming fields to sheet columns/i)
+    expect(code).toMatch(/try\s*\{/)
+    expect(code).toMatch(/catch\s*\(e\)/)
+
+    // README includes setup and mapping hint
+    expect(readme).toMatch(/Apps Script/i)
+    expect(readme).toMatch(/Deploy as Web App/i)
+    expect(readme).toMatch(/Map fields to columns/i)
+  })
+
+  it('respects exclude mode', () => {
+    const extras = buildExtrasForPage(basePage, { sheetsMode: 'exclude' })
+    expect(Object.keys(extras).some(k => k.startsWith('sheets/'))).toBe(false)
+  })
+})