nu: add Alt+. last-arg keybinding and nushell-book doc submodule

- keybindings block in config.nu with Alt+. → insert last token from history
- nushell.github.io added as external_nushell-book submodule under dot_local/share/docs
- CLAUDE.md local docs table updated

.gitmodules

@@ -7,3 +7,6 @@
 [submodule "dot_local/share/docs/external_waybar.wiki"]
 	path = dot_local/share/docs/external_waybar.wiki
 	url = https://github.com/Alexays/Waybar.wiki.git
+[submodule "dot_local/share/docs/external_nushell-book"]
+	path = dot_local/share/docs/external_nushell-book
+	url = https://github.com/nushell/nushell.github.io.git

CLAUDE.md

@@ -64,6 +64,7 @@ This copies built theme artifacts into the appropriate `dot_config/*/themes/` di
 | chezmoi | `~/.local/share/docs/chezmoi-docs/` |
 | Hyprland | `~/.local/share/docs/hyprland.wiki/` |
 | Waybar | `~/.local/share/docs/waybar.wiki/` (also `man 5 waybar`) |
+| Nushell | `~/.local/share/docs/nushell-book/` |
 | Ghostty | `/usr/share/ghostty` |
 
 ## Commit convention

dot_config/nushell/config.nu.tmpl

@@ -30,6 +30,19 @@ $env.config = {
       completer: $carapace_completer
     }
   }
+
+  keybindings: [
+    {
+      name: insert_last_arg
+      modifier: alt
+      keycode: char_.
+      mode: [vi_insert, emacs]
+      event: {
+        send: executehostcommand
+        cmd: "commandline edit --insert (history | last | split words | last)"
+      }
+    }
+  ]
 }
 
 plugin use gstat