fix(mindspace): 生成页面统一使用中文友好无衬线字体

页脚品牌行、纯文字页面模板与技能提示词此前用 Georgia/Times 衬线体，中文渲染
效果差；统一改为系统无衬线字体栈（PingFang SC / Microsoft YaHei 等）。

Co-authored-by: Cursor <cursoragent@cursor.com>

mindspace-page-tag.mjs

@@ -2,6 +2,8 @@ export const MINDSPACE_PAGE_TAG_ATTR = 'data-mindspace-page-tag';
 export const MINDSPACE_PAGE_TAG_PLATFORM_BRAND = 'platform-brand';
 export const PLATFORM_BRAND_TEXT = 'TKMind · 智趣';
 export const PLATFORM_BRAND_STYLE_ID = 'mindspace-platform-brand-style';
+export const MINDSPACE_PAGE_FONT_STACK =
+  '-apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif';
 
 const PLATFORM_BRAND_VISIBILITY_STYLE = `<style id="${PLATFORM_BRAND_STYLE_ID}">
 [data-mindspace-page-tag="${MINDSPACE_PAGE_TAG_PLATFORM_BRAND}"] {
@@ -9,9 +11,10 @@ const PLATFORM_BRAND_VISIBILITY_STYLE = `<style id="${PLATFORM_BRAND_STYLE_ID}">
   opacity: 1 !important;
   visibility: visible !important;
   color: #9aa3a0 !important;
+  font-family: ${MINDSPACE_PAGE_FONT_STACK} !important;
   font-size: 12px !important;
-  font-weight: 600 !important;
-  letter-spacing: 0.08em !important;
+  font-weight: 500 !important;
+  letter-spacing: 0.02em !important;
   text-shadow: 0 1px 3px rgba(0, 0, 0, 0.35);
 }
 </style>`;

mindspace-page-tag.test.mjs

@@ -39,6 +39,7 @@ test('injectPlatformBrandVisibilityStyle adds readable brand css', () => {
   const result = injectPlatformBrandVisibilityStyle(html);
   assert.match(result, new RegExp(`id="${PLATFORM_BRAND_STYLE_ID}"`));
   assert.match(result, /opacity:\s*1 !important/);
+  assert.match(result, /font-family:.*PingFang SC/);
 });
 
 test('ensurePlatformBrandFooter appends brand line when marker is missing', () => {

mindspace-pages.mjs

@@ -185,7 +185,7 @@ function renderPreviewHtml(page) {
   <meta http-equiv="Content-Security-Policy" content="default-src 'none'; style-src 'unsafe-inline'; img-src data:; font-src 'none'; base-uri 'none'; form-action 'none'">
   <title>${escapeHtml(page.title)}</title>
   <style>
-    :root { color: #18211d; background: #f5f0e5; font-family: Georgia, "Times New Roman", serif; }
+    :root { color: #18211d; background: #f5f0e5; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif; }
     * { box-sizing: border-box; }
     body { margin: 0; padding: clamp(24px, 7vw, 88px); background: radial-gradient(circle at 90% 0, #d8e8df, transparent 34rem), #f5f0e5; }
     article { width: min(820px, 100%); margin: 0 auto; padding: clamp(28px, 6vw, 72px); border: 1px solid #d7d0c1; border-radius: 28px; background: rgba(255,253,247,.94); box-shadow: 0 24px 70px rgba(45,53,47,.12); }

public/thumbnail-demo-samples/vietnam-guide-bad.html

@@ -6,7 +6,7 @@
   <title>越南旅游指南</title>
   <style>
     :root { --accent: #2f6f57; --bg: #f4f0e7; }
-    body { margin: 0; font-family: Georgia, serif; background: var(--bg); color: #18211d; line-height: 1.7; }
+    body { margin: 0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif; background: var(--bg); color: #18211d; line-height: 1.7; }
     main { max-width: 720px; margin: 0 auto; padding: 48px 24px 72px; }
     h1 { font-size: 2.2rem; margin-bottom: 0.5rem; color: var(--accent); }
     .lead { color: #5f6963; margin-bottom: 2rem; }

public/thumbnail-demo-samples/vietnam-guide-good.html

@@ -8,7 +8,7 @@
   <title>越南旅游指南</title>
   <style>
     :root { --accent: #ff6b35; --accent2: #24243e; --bg: #fff8f2; }
-    body { margin: 0; font-family: Georgia, serif; background: linear-gradient(160deg, var(--bg), #ffe8d6); color: #18211d; line-height: 1.7; }
+    body { margin: 0; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif; background: linear-gradient(160deg, var(--bg), #ffe8d6); color: #18211d; line-height: 1.7; }
     .hero { position: relative; height: 280px; overflow: hidden; }
     .hero img { width: 100%; height: 100%; object-fit: cover; display: block; }
     .hero::after { content: ''; position: absolute; inset: 0; background: linear-gradient(to top, rgba(36,36,62,0.55), transparent 60%); }

user-publish.mjs

@@ -239,6 +239,7 @@ npm run check:mindspace-cover
 - 完整 \`<!DOCTYPE html>\`，\`lang="zh-CN"\`
 - 移动端友好：\`<meta name="viewport" content="width=device-width, initial-scale=1">\`
 - 深色/浅色与内容一致；主色在 CSS 与 mindspace-cover 中保持一致
+- 中文页面优先使用系统无衬线字体：\`-apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif\`；**避免** Georgia、Times 等西文衬线体
 - 页脚平台品牌行**必须**使用 \`data-mindspace-page-tag="platform-brand"\` 标记，显示为 **TKMind · 智趣**，**禁止**使用邮箱或 \`tkmind.ai\`
 
 \`\`\`html