refactor(mackup): transition to copy-based backup and restore

- Updated `ssr sync` and `ssr restore` commands to use `mackup backup` and `mackup restore`, replacing the previous symlink-based approach.
- Added guidance for users with legacy symlink setups to run `ssr mackup unlink` for recovery.
- Revised documentation in README, completions, and configuration examples to reflect the new copy-based methodology for improved reliability on newer macOS versions.
- Enhanced comments in the codebase to clarify the changes and their implications for users.

Co-authored-by: Cursor <cursoragent@cursor.com>

bin/ssr-mackup

@@ -5,8 +5,8 @@
 #   scan    Per-item prompts for new ~/.mackup/ssr-*.cfg files.
 #   list    List existing ~/.mackup/ssr-*.cfg files with the path they cover.
 #   clean   Remove all generated ssr-*.cfg files (prompts first).
-#   unlink  Run `mackup link uninstall` — copy configs back from Mackup
-#           storage and remove symlinks (fixes broken iTerm / shell paths).
+#   unlink  Run `mackup link uninstall` — only for undoing symlink-based Mackup
+#           (legacy SSR or manual `mackup link`); copies from storage and removes symlinks.
 
 set -euo pipefail
 SSR_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
@@ -31,14 +31,14 @@ Subcommands:
   scan    Suggest new ~/.mackup/ssr-*.cfg files (confirm each item).
   list    List existing generated files.
   clean   Remove all generated ssr-*.cfg files.
-  unlink  Revert Mackup symlinks (copy from cloud → real files in ~).
+  unlink  Undo symlink-based Mackup only (`mackup link uninstall`).
 
 Run 'ssr mackup scan' when new dot-dirs appear; commit ~/.mackup/ssr-*.cfg
 with your dotfiles if you use them.
 
-If Terminal/iTerm or other apps break after sync, run:
+If you previously used symlink-based Mackup and apps break, run:
   ssr mackup unlink
-That runs Mackup's official undo for symlink-based installs.
+Current SSR uses copy-based `mackup backup` / `restore` instead.
 EOF
 }
 
@@ -259,11 +259,11 @@ cmd_unlink() {
 This runs:  mackup -f link uninstall
 
 Mackup copies each managed path from your Mackup storage folder back into
-$HOME and removes the symlinks. Use when settings broke after `ssr sync` /
-`mackup link install` (e.g. iTerm2, shell init files pointing at iCloud).
+$HOME and removes the symlinks. Use only if you still have symlink-based
+Mackup from an older SSR or from manual `mackup link` / `link install`.
 
-After unlink, apps use normal local files again. Run `ssr sync` only when
-you are ready to re-apply symlink-based backup.
+After unlink, apps use normal local files again. Ongoing `ssr sync` uses
+`mackup backup` (copy to cloud), not symlinks.
 EOF
     printf '\n'
     ssr::confirm "Run mackup link uninstall now?" 120 || { printf 'Aborted.\n'; return 0; }