feat: 完成 DOCX R4 元素级视觉门禁

建立 Chromium、Word 与 WPS 的可编辑内容、段落几何、页眉页脚、封面、媒体和逐页视觉比较链路。

支持封面独立分节、正文页码重启、主题页边距与横向纸张，并将自然分页差异降为诊断项。

修正代码块内边距和折叠表格单元格边框映射，14 套主题生产矩阵与六组布局视觉矩阵通过。

themes/formal-feasibility/theme.css

@@ -10,7 +10,7 @@
 #write {
   color: var(--feasibility-ink);
   font-family:
-    "Noto Serif CJK SC", "Source Han Serif SC",
+    "FandolSong", "Noto Serif CJK SC", "Source Han Serif SC",
     "Microsoft YaHei", "SimSun", serif;
   font-size: 17px;
   line-height: 1.8;
@@ -70,7 +70,7 @@
 #write h3,
 #write h4 {
   font-family:
-    "Noto Sans CJK SC", "Source Han Sans SC",
+    "FandolHei", "Noto Sans CJK SC", "Source Han Sans SC",
     "Microsoft YaHei", sans-serif;
   font-weight: 700;
 }

themes/formal-feasibility/theme.json

@@ -21,6 +21,31 @@
       "left": "30mm"
     }
   },
+  "docxFonts": {
+    "faces": [
+      {
+        "family": "FandolSong",
+        "aliases": ["Noto Serif CJK SC", "Source Han Serif SC", "SimSun"],
+        "source": "theme-shared:official-fonts/FandolSong-Regular.woff2",
+        "weight": 400,
+        "license": "GPL-3.0-or-later WITH Font-exception-2.0"
+      },
+      {
+        "family": "FandolSong",
+        "aliases": ["Noto Serif CJK SC", "Source Han Serif SC", "SimSun"],
+        "source": "theme-shared:official-fonts/FandolSong-Bold.woff2",
+        "weight": 700,
+        "license": "GPL-3.0-or-later WITH Font-exception-2.0"
+      },
+      {
+        "family": "FandolHei",
+        "aliases": ["Noto Sans CJK SC", "Source Han Sans SC", "SimHei", "Microsoft YaHei"],
+        "source": "theme-shared:official-fonts/FandolHei-Regular.woff2",
+        "weight": 400,
+        "license": "GPL-3.0-or-later WITH Font-exception-2.0"
+      }
+    ]
+  },
   "docxStyle": {
     "preset": "formal"
   },