refactor: migrate from shell-based sync to mise dotfiles management

- Replace sync-config/sync-script with mise.toml [dotfiles] directives
- Convert installer scripts to mise tasks (shells, desktop, theme, webapps)
- Remove config/nvim-old (deprecated neovim config)
- Add omarchy theme system with multi-app configs (btop, hyprland, kitty, foot, tmux, etc.)
- Move SSH hosts to config.d/* include pattern
- Add Tera templates for dynamic config generation (git-local, dofiles.conf)
- Update pi agent settings (0.80.10, packages list)
- Add mise tasks for pi plugin setup and nvim tooling

installer/01-install-cachy.sh

@@ -2,14 +2,12 @@
 # SjB TODO:
 # - install public keys
 
-sudo pacman -Syu --noconfirm
-
 if [[ "$(uname -m)" == "x86_64" ]]; then
 
     if ! pacman-key --list-keys 882DCFE48E2051D48E2562ABF3B607488DB35A47 >/dev/null 2>&1; then
         sudo pacman-key --recv-key 882DCFE48E2051D48E2562ABF3B607488DB35A47 && sudo pacman-key --lsign-key 882DCFE48E2051D48E2562ABF3B607488DB35A47
     fi
-    if sudo pacman -U --noconfirm https://cdn77.cachyos.org/repo/x86_64/cachyos/archlinux-keyring-20260420-2-any.pkg.tar.zst &&
+    if sudo pacman -U --noconfirm https://cdn77.cachyos.org/repo/x86_64/cachyos/archlinux-keyring-20260707.1-1-any.pkg.tar.zst &&
         sudo pacman -U --noconfirm https://cdn77.cachyos.org/repo/x86_64/cachyos/cachyos-mirrorlist-27-1-any.pkg.tar.zst; then
 
     if ! grep -q "^\[cachyos\]" /etc/pacman.conf; then