Introduce list/restore/delete commands for skill backups created during
uninstall. Restore copies files back to SSOT, saves the DB record, and
syncs to the current app with rollback on failure. Delete removes the
backup directory after a confirmation dialog. ConfirmDialog gains a
configurable zIndex prop to support nested dialog stacking.
Create a local backup under ~/.cc-switch/skill-backups/ before removing
skill directories. The backup includes all skill files and a meta.json
with original skill metadata. Old backups are pruned to keep at most 20.
The backup path is returned to the frontend and shown in the success
toast. Bump version to 3.12.3.
Skills import previously inferred app enablement from filesystem presence,
causing incorrect multi-app activation when the same skill directory existed
under multiple app paths. Now the frontend submits explicit app selections
via ImportSkillSelection, and schema migration preserves a snapshot of
legacy app mappings to avoid lossy reconstruction.
Also adds reconciliation to sync_to_app (removes disabled/orphaned symlinks)
and MCP sync_all_enabled (removes disabled servers from live config).
