refactor: switch to catppuccin mocha across tmux and neovim

- tmux: hand-rolled catppuccin theme, three-way status bar toggle, plugin cleanup
- nvim: switch colorscheme to catppuccin-mocha, update lualine colors
- nvim: add tmuxline.vim for tmux statusline generation
- kitty: fix MesloLGS NF font typo, remove deprecated config keys

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

kitty/keymap.conf

@@ -30,7 +30,7 @@ map ctrl+shift+u input_unicode_character
 map ctrl+home resize_window reset
 
 # Text Selection & Search
-map ctrl+shift+f show_scrollback
+map ctrl+shift+o show_scrollback
 map ctrl+shift+h show_last_command_output
 map cmd+f launch --type=overlay --stdin-source=@screen_scrollback /usr/bin/less +G -R
 
@@ -40,6 +40,13 @@ map cmd+minus change_font_size all -2.0
 map cmd+0 change_font_size all 0
 
 # Background Opacity
+# Fast opacity controls
+map cmd+alt+up set_background_opacity +0.05
+map cmd+alt+down set_background_opacity -0.05
+map cmd+alt+t remote_control set-background-opacity --toggle 0.85
+map cmd+alt+backspace set_background_opacity default
+
+# Prefix-based opacity controls (existing)
 map ctrl+shift+a>m set_background_opacity +0.1
 map ctrl+shift+a>l set_background_opacity -0.1
 map ctrl+shift+a>1 set_background_opacity 1
@@ -57,4 +64,3 @@ map ctrl+shift+g show_last_command_output
 
 # German character mappings
 map alt+s send_text all ß
-