feat(docs): add auto-generated Markdown wiki

Adds docs/split-wiki.py, a Python script that splits fish-config.md
into a multi-page Markdown wiki under docs/wiki/:

- index.md: DESCRIPTION intro + full section ToC
- one file per numbered section (1-configuration-variables.md … 9-viewing-this-manual.md)
- each section page has a nav bar at the top linking to every other section

The build-docs.yml workflow now runs the script alongside pandoc so all
three formats (man page, HTML, wiki) are regenerated together from a
single source in one CI run.

README slimmed down to a pointer to the wiki; docs/fish-config.md §9
gains an "As a wiki" subsection.

docs/wiki/2-path-setup.md

@@ -0,0 +1,22 @@
+# 2. PATH SETUP
+
+**Sections:** [Index](index.md) | [1. Configuration Variables](1-configuration-variables.md) | **2. Path Setup** | [3. Key Bindings](3-key-bindings.md) | [4. Abbreviations](4-abbreviations.md) | [5. Functions Reference](5-functions-reference.md) | [6. Dependency Catalog](6-dependency-catalog.md) | [7. Customization](7-customization.md) | [8. Fisher Plugins](8-fisher-plugins.md) | [9. Viewing This Manual](9-viewing-this-manual.md)
+
+---
+
+Directories prepended to PATH in this order (first wins):
+
+    ~/.local/bin              Standard user-local executables
+    ~/Applications            User-installed standalone apps
+    ~/scripts                 Personal shell scripts
+    ~/bin                     Cargo binaries (appended — lowest priority)
+    $BUN_INSTALL/bin          Bun runtime and global packages
+    $NPM_CONFIG_PREFIX/bin    Global npm packages
+    ~/.lmstudio/bin           LM Studio CLI
+    ~/.resend/bin             Resend CLI
+    ~/.fzf/bin                fzf binary (git-installed)
+
+Cargo binaries are intentionally appended (lowest priority) to avoid
+shadowing system-installed Rust tools.
+
+---