feat(latex): 新增 LaTeX 排版系统，从 Markdown 生成 ctexbook

- 新增 officefile/latex/ 目录，包含 main.tex、preamble.tex 及 14 个章节 + 10 个附录 tex 文件
- md→tex 转换流程：pandoc 转换 + _postprocess.py 后处理（去编号、修破折号、清标签）
- 修复 5 个 md 源文件的标题层级（H1→H2 降级，统一层级结构）
- 配置 VS Code LaTeX Workshop（xelatex + ctexbook 编译链）
- 新增 VS Code workspace 和 .gitignore（排除 LaTeX 编译产物）

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

officefile/latex/preamble.tex

@@ -0,0 +1,92 @@
+% ========== 页面布局 ==========
+\usepackage[top=2.54cm, bottom=2.54cm, left=3.17cm, right=3.17cm]{geometry}
+
+% ========== 行距 ==========
+\usepackage{setspace}
+\onehalfspacing
+
+% ========== 修复页眉高度警告 ==========
+\setlength{\headheight}{14.49998pt}
+
+% ========== 页眉页脚 ==========
+\usepackage{fancyhdr}
+\pagestyle{fancy}
+\fancyhf{}
+\fancyhead[LE]{\thepage}
+\fancyhead[RE]{\leftmark}
+\fancyhead[LO]{\rightmark}
+\fancyhead[RO]{\thepage}
+\renewcommand{\headrulewidth}{0.4pt}
+
+% ========== 数学 ==========
+\usepackage{amsmath,amssymb,mathtools}
+
+% ========== 表格 ==========
+\usepackage{booktabs}
+\usepackage{tabularx}
+\usepackage{multirow}
+\usepackage{longtable}
+
+% ========== 图形 ==========
+\usepackage{graphicx}
+\usepackage{subfig}
+\graphicspath{{figures/}{figures/ch01/}{figures/ch02/}{figures/ch03/}{figures/ch04/}{figures/ch05/}{figures/ch06/}{figures/ch07/}{figures/ch08/}{figures/ch09/}{figures/ch10/}{figures/ch11/}{figures/ch12/}{figures/ch13/}}
+
+% ========== 代码 ==========
+\usepackage{listings}
+\lstset{
+  basicstyle=\ttfamily\small,
+  breaklines=true,
+  frame=single,
+  backgroundcolor=\color{gray!10},
+  keywordstyle=\color{blue},
+  commentstyle=\color{green!60!black},
+  stringstyle=\color{red},
+  numbers=left,
+  numberstyle=\tiny\color{gray},
+  xleftmargin=2em,
+}
+
+% ========== 颜色 ==========
+\usepackage{xcolor}
+
+% ========== 超链接 ==========
+\usepackage{hyperref}
+\usepackage{bookmark}
+\hypersetup{
+  colorlinks=true,
+  linkcolor=blue!70!black,
+  citecolor=green!50!black,
+  urlcolor=blue!80!black,
+  bookmarksopen=true,
+}
+
+% ========== 其他 ==========
+\usepackage{enumitem}
+\usepackage{tcolorbox}
+
+% ========== 修复 pandoc longtable 无标题表格 ==========
+\newcounter{none}
+
+% ========== 修复 pandoc tightlist ==========
+\providecommand{\tightlist}{}
+
+% ========== 修复 pandoc passthrough ==========
+\providecommand{\passthrough}[1]{#1}
+
+% ========== 章节格式 ==========
+\ctexset{
+  chapter = {
+    format = \huge\bfseries\centering,
+    nameformat = {},
+    titleformat = {},
+    beforeskip = 1ex,
+    afterskip = 2ex,
+  },
+  section = {
+    format = \Large\bfseries,
+  },
+  subsection = {
+    format = \large\bfseries,
+  },
+}