Add work nvim language pack, switch tmux prefix to Ctrl-Space

Work language support (C#, TS, JS, CSS, HTML, Prettier) is now gated
behind a stow-loaded work-languages.lua module so it only activates
when the work package is stowed. Tmux prefix changed from Ctrl-b to
Ctrl-Space to match the neovim Space-leader feel.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

laptop/.config/tmux/tmux.conf

@@ -1,5 +1,10 @@
 # tmux.conf — vim-style keybindings
 
+# Prefix
+set -g prefix C-Space
+unbind C-b
+bind C-Space send-prefix
+
 # Splits
 unbind '"'
 unbind %