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/8-fisher-plugins.md

@@ -0,0 +1,32 @@
+# 8. FISHER PLUGINS
+
+**Sections:** [Index](index.md) | [1. Configuration Variables](1-configuration-variables.md) | [2. Path Setup](2-path-setup.md) | [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** | [9. Viewing This Manual](9-viewing-this-manual.md)
+
+---
+
+Fisher is bootstrapped automatically on the **first interactive session** via
+`conf.d/first_run.fish`. This also applies the Catppuccin Mocha theme and
+prints a one-time welcome message. Subsequent sessions skip all first-run
+logic with zero overhead.
+
+To re-trigger first-run initialization (e.g., after a fresh install or for
+testing), run:
+
+    set -Ue __fish_config_first_run_complete
+
+Then open a new shell.
+
+The plugin list is maintained in fish_plugins at the config root.
+
+    jorgebucaran/fisher           Plugin manager itself
+    catppuccin/fish               Catppuccin Mocha color theme
+    PatrickF1/fzf.fish            fzf integration for Fish
+    franciscolourenco/done        Desktop notification when long commands finish
+    jorgebucaran/autopair.fish    Auto-pair brackets and quotes
+    meaningful-ooo/sponge         Remove failed commands from history
+    nickeb96/puffer-fish          !! / !$ / ./ expansion
+
+Run `fisher update` to update all plugins, or `fish-deps update` which
+calls fisher update as its first step.
+
+---