feat: custom kitty tab bar with system status + install scripts

Custom tab_bar.py with flat tabs, right-aligned status area (git branch,
CPU%, memory, uptime, hostname, clock) using Nerd Font icons. F12/Shift+F12
toggle for tab bar. Added Kitty-setup.md, theme-setup.md, and install
scripts for kitty-only and full Debian theme deployment.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

kitty/kitty-theme.conf

@@ -1,10 +1,37 @@
 # Seth Linux Theme — kitty overrides
 # Include from kitty.conf: include ~/path/to/kitty-theme.conf
 
-tab_bar_edge top
 allow_remote_control yes
+listen_on unix:/tmp/kitty-{kitty_pid}
 wayland_titlebar_color #000000
 macos_titlebar_color #000000
 hide_window_decorations yes
 window_border_width 0
 draw_minimal_borders yes
+
+# ── Status bar (tab bar at top) ──────────────────
+tab_bar_edge top
+tab_bar_min_tabs 1
+tab_bar_style custom
+tab_powerline_style round
+tab_bar_align left
+tab_title_template " {index}: {title} "
+active_tab_title_template " {index}: {title} "
+tab_title_max_length 40
+
+# Colors — Sethian dark + orange
+active_tab_foreground   #000000
+active_tab_background   #D35400
+active_tab_font_style   bold
+inactive_tab_foreground #888888
+inactive_tab_background #1a1a1a
+inactive_tab_font_style normal
+tab_bar_background      #0d0d0d
+tab_bar_margin_height   2.0 0.0
+
+# Refresh tab bar for clock updates
+tab_bar_timeout 60.0
+
+# Toggle tab/status bar
+map f12 remote_control load-config --override tab_bar_min_tabs=999
+map shift+f12 remote_control load-config --override tab_bar_min_tabs=1