feat: add Catppuccin Mocha theme to tmux config

Apply consistent Catppuccin Mocha colours across status bar, window titles,
pane borders, message prompt, copy mode, and clock to match kitty and other
configs in the repo.

.tmux.conf

@@ -0,0 +1,57 @@
+unbind C-b
+
+set-option -g prefix C-space
+bind-key C-space send-prefix
+
+set -g mouse on
+
+set -s extended-keys on
+set -as terminal-features 'xterm-kitty:extkeys'
+set -s set-clipboard on
+
+# Catppuccin Mocha colours
+base=#1e1e2e
+mantle=#181825
+crust=#11111b
+surface0=#313244
+surface1=#45475a
+surface2=#585b70
+text=#cdd6f4
+subtext1=#bac2de
+subtext0=#a6adc8
+lavender=#b4befe
+mauve=#cba6f7
+blue=#89b4fa
+teal=#94e2d5
+green=#a6e3a1
+yellow=#f9e2af
+red=#f38ba8
+rosewater=#f5e0dc
+
+# Status bar
+set -g status-style "bg=$mantle,fg=$text"
+set -g status-left-length 40
+set -g status-right-length 80
+set -g status-left "#[bg=$mauve,fg=$crust,bold] #S #[bg=$mantle,fg=$mauve]"
+set -g status-right "#[fg=$blue]  %H:%M #[fg=$surface2]│#[fg=$subtext0] %d %b "
+set -g status-justify left
+set -g status-interval 5
+
+# Window titles
+set -g window-status-format "#[fg=$surface2] #I #[fg=$subtext0]#W "
+set -g window-status-current-format "#[fg=$mantle,bg=$lavender] #I #[fg=$crust,bg=$blue,bold] #W "
+set -g window-status-separator ""
+
+# Pane borders
+set -g pane-border-style "fg=$surface0"
+set -g pane-active-border-style "fg=$lavender"
+
+# Message / command prompt
+set -g message-style "bg=$surface0,fg=$text"
+set -g message-command-style "bg=$surface0,fg=$blue"
+
+# Copy mode highlight
+set -g mode-style "bg=$surface1,fg=$rosewater"
+
+# Clock mode
+set -g clock-mode-colour "$blue"