feat(scaffolds): manual 模板补字体栈 + md-to-docx 模板更新

manual/main.tex: Cambria/SimSun(SimHei/KaiTi)/Courier New，
均用 \IfFontExistsTF 守卫，缺字体回退 ctex 默认集，不破坏可移植性。

mytoolkit/scaffolds/manual/main.tex

@@ -16,6 +16,14 @@
 \usepackage{enumitem}
 \usepackage{hyperref}
 
+% ---- fonts (Cambria + SimSun/SimHei/KaiTi; falls back to ctex default set) ----
+\IfFontExistsTF{Cambria}{\setmainfont{Cambria}}{}
+\IfFontExistsTF{SimSun}{%
+  \setCJKmainfont[BoldFont={SimHei},ItalicFont={KaiTi}]{SimSun}%
+  \setCJKsansfont[BoldFont={SimHei}]{SimHei}%
+}{}
+\IfFontExistsTF{Courier New}{\setmonofont{Courier New}}{\setmonofont{Menlo}}
+
 % ---- palette (keep in sync with templates/md-to-pdf/manual/template.typ) ----
 \definecolor{primary}{HTML}{1F4E79}
 \definecolor{secondary}{HTML}{2C3E50}