Remove the restriction that prevented users from deleting built-in
patterns (those with IDs prefixed 'pattern-'). Built-in patterns are
intended as starting points, not permanent fixtures.
Changes:
- Add deletedBuiltinPatternIds field to WorkspaceState to track which
built-in patterns the user has removed
- Update mergePatterns to skip deleted built-ins during workspace load,
preventing them from being re-added
- Remove the isBuiltinPattern guard from AryxAppService.deletePattern;
when a built-in is deleted, its ID is recorded in the tracking list
- Enable the delete button in SettingsPanel and PatternEditor for all
patterns (keep the 'Built-in pattern' label for context)
- Add 3 tests covering built-in deletion, custom deletion, and
selectedPatternId fallback
Users can still restore deleted built-ins via workspace reset.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
