feat(themes): add theme system with starship integration

- Add theme selection system with 5 predefined themes
- Implement Catppuccin Mocha, Dracula, Gruvbox Dark, Nord, and Tokyo Night
- Each theme includes NvChad integration and starship prompt configuration
- Support for custom color palettes and consistent formatting
- Interactive theme selection with numbered menu

lib/themes/nord.sh

@@ -0,0 +1,92 @@
+#!/bin/bash
+THEME_DISPLAY_NAME="Nord"
+NVCHAD_THEME="nord"
+
+write_starship_config() {
+  cat >"$1" <<'TOML'
+palette = "nord"
+format = """$directory$git_branch$git_status$character"""
+
+[directory]
+style = "bold fg:bright-yellow"
+truncation_length = 3
+
+[git_branch]
+style = "bold fg:bright-green"
+format = " [$branch]($style) "
+
+[git_status]
+style = "bold fg:bright-red"
+
+[character]
+success_symbol = "[❯](bold fg:bright-green)"
+error_symbol = "[❯](bold fg:bright-red)"
+
+[palettes.nord]
+bright-yellow = "#ebcb8b"
+bright-green = "#a3be8c"
+bright-red = "#bf616a"
+bright-blue = "#81a1c1"
+bright-purple = "#b48ead"
+bright-aqua = "#88c0d0"
+bright-orange = "#d08770"
+TOML
+}
+
+write_zellij_config() {
+  cat >"$1" <<'KDL'
+theme "nord"
+default_layout "default"
+default_mode "normal"
+pane_frames false
+simplified_ui true
+mouse_mode false
+
+keybinds {
+    shared {
+        bind "Alt h" { MoveFocusOrTab "Left"; }
+        bind "Alt l" { MoveFocusOrTab "Right"; }
+        bind "Alt j" { MoveFocus "Down"; }
+        bind "Alt k" { MoveFocus "Up"; }
+        bind "Alt n" { NewPane "Down"; }
+        bind "Alt v" { NewPane "Right"; }
+        bind "Alt f" { ToggleFloatingPanes; }
+        bind "Alt t" { NewTab; }
+    }
+}
+
+themes {
+    nord {
+        fg "#d8dee9"
+        bg "#2e3440"
+        black "#3b4252"
+        red "#bf616a"
+        green "#a3be8c"
+        yellow "#ebcb8b"
+        blue "#81a1c1"
+        magenta "#b48ead"
+        cyan "#88c0d0"
+        white "#e5e9f0"
+        orange "#d08770"
+    }
+}
+KDL
+}
+
+write_lazygit_config() {
+  cat >"$1" <<'YAML'
+gui:
+  theme:
+    activeBorderColor:
+      - "#ebcb8b"
+      - bold
+    inactiveBorderColor:
+      - "#4c566a"
+    selectedLineBgColor:
+      - "#3b4252"
+    cherryPickedCommitFgColor:
+      - "#a3be8c"
+    defaultFgColor:
+      - "#d8dee9"
+YAML
+}