fix: TUI mit drei Backends (gum/whiptail/basic) + gum auto-install auf frischen Systemen

- tui.sh: komplett überarbeitet mit _strip_format() für basic mode
- whiptail als mittleres Fallback-Backend hinzugefügt
- Alle #{bold}/#{normal}-Markups entfernt, saubere ANSI-API (tui_info/tui_bold/...)
- install.sh: detect_environment() installiert gum vor allen Prompts
- Kein seq-Dependency mehr (printf -v statt seq)
- packages.sh/preflight.sh/homelab.sh/optional.sh auf neue TUI-API migriert

modules/homelab/setup.sh

@@ -17,9 +17,9 @@ module_main() {
   local homelab_config_dir="$HOME/.config/homelab"
   local homelab_config_file="$homelab_config_dir/config.yaml"
 
-  tui_format "#{bold}Homelab Control Center Setup#{normal}"
-  tui_format "This configures SSH access and connection details to your Unraid server."
-  tui_format ""
+  tui_bold "Homelab Control Center Setup"
+  tui_info "This configures SSH access and connection details to your Unraid server."
+  printf '\n'
 
   local server_address server_username
 
@@ -59,13 +59,12 @@ CONFIG
 
   log_success "Homelab configuration saved to $homelab_config_file"
 
-  tui_format ""
-  tui_format "#{bold}Configuration Summary:#{normal}"
-  tui_format "  Server address: ${server_address}"
-  tui_format "  SSH username:   ${server_username}"
-  tui_format ""
-  tui_format "You can edit the configuration anytime at:"
-  tui_format "  ${homelab_config_file}"
+  printf '\n'
+  tui_bold "Configuration Summary:"
+  tui_info "  Server address: ${server_address}"
+  tui_info "  SSH username:   ${server_username}"
+  printf '\n'
+  tui_info "You can edit the configuration anytime at: ${homelab_config_file}"
 
   if tui_confirm "Test SSH connection to ${server_username}@${server_address}?"; then
     log_info "Testing SSH connection..."