🤖 feat: add mdBook-pagetoc for in-page table of contents

Added mdbook-pagetoc preprocessor to generate automatic table of contents
for documentation pages.

Benefits:
- Improves navigation for long pages (especially API reference)
- Shows page structure at a glance
- Better user experience when browsing documentation

Uses: https://github.com/JorelAli/mdBook-pagetoc

Generated with cmux

Author: ammar-agent

.gitignore

@@ -112,3 +112,7 @@ test_hot_reload.sh
 
 # TypeDoc
 .typedoc/
+
+# mdBook pagetoc (auto-generated)
+docs/theme/pagetoc.css
+docs/theme/pagetoc.js

docs/book.toml

@@ -13,11 +13,13 @@ use-default-preprocessors = true
 [preprocessor.mermaid]
 command = "mdbook-mermaid"
 
+[preprocessor.pagetoc]
+
 [output.html]
 git-repository-url = "https://github.com/coder/cmux"
 edit-url-template = "https://github.com/coder/cmux/edit/main/docs/{path}"
-additional-js = ["mermaid.min.js", "mermaid-init.js"]
-additional-css = ["theme/custom.css"]
+additional-js = ["mermaid.min.js", "mermaid-init.js", "theme/pagetoc.js"]
+additional-css = ["theme/custom.css", "theme/pagetoc.css"]
 default-theme = "navy"
 preferred-dark-theme = "navy"
 favicon = "theme/favicon.webp"