feat(emacs): robust Nix-based Emacs setup with daemon service, improved elisp dev, and full package documentation

- Emacs daemon runs as a systemd service via Nix
- Modular Emacs config with Nix-managed packages (elisp-slime-nav, aggressive-indent, highlight-defined, etc.)
- Keybinding fixes and error handling improvements
- New EMACS_README.md explains ecosystem and troubleshooting
- Nix config: GUI sudo askpass, podman, and desktop tweaks
- All errors from missing packages and keybindings resolved

modules/development/emacs.nix

@@ -75,6 +75,7 @@ with lib; let
         json-mode
         yaml-mode
         markdown-mode
+        lsp-scheme
 
         # Org mode and knowledge management
         org
@@ -82,6 +83,7 @@ with lib; let
         org-roam-ui
 
         # UI enhancements
+        highlight-defined
         doom-themes
         doom-modeline
         all-the-icons
@@ -89,6 +91,8 @@ with lib; let
         highlight-indent-guides
 
         # Editing enhancements
+        elisp-slime-nav
+        aggressive-indent
         smartparens
         expand-region
         multiple-cursors