Phase 118 complete:
- migration 20260512_000109 adds single global Fakturownia settings row
- FakturowniaIntegrationRepository simplified to one-instance API
- FakturowniaIntegrationController + edit view collapsed to one settings page
- Integrations hub shows Fakturownia as single instance
- Invoice config delegated flow always uses global integration_id
Note: shared routes/web.php and DOCS/* updates from Phase 118 are bundled
into the follow-up feat(121+122) commit because Phase 121/122 modified the
same files; hunk-level split was not performed.
Co-Authored-By: Claude <noreply@anthropic.com>