feat(helpdesk): add handover protocol management

Implement handover protocols as a new entity in the helpdesk module,
allowing users to create fillable protocol records from admin-defined
software product schemas.

Key additions:
- DB migration (helpdesk_handovers table) with tenant scope
- HandoverService with status workflow (draft/in_progress/completed/archived)
- Three-tier permissions (view/create/manage)
- Two-step creation wizard (Stripe-style assistant)
- Grid.js list page with search and status filter
- Edit/detail page with aside metadata and status controls
- Reusable core autocomplete lookup component (app-lookup-field)
- Debitor lookup data endpoint for autocomplete
- Dynamic form rendering from schema snapshots
- 11 PHPUnit tests for HandoverService
- DE+EN i18n translations (48 keys each)

Also includes: PHPStan fixes (dead code removal, stale baseline cleanup),
software product edit title improvement, fieldset simplification,
and Stripe-style hover for schema preview.

Workflow: HD-HANDOVERS-001 (.agents/runs/HD-HANDOVERS-001/)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

config/assets.php

@@ -45,6 +45,7 @@ return [
                 'css/components/app-breadcrumb.css',
                 'css/components/app-tile.css',
                 'css/components/app-tooltips.css',
+                'css/components/app-lookup-field.css',
                 'css/components/app-page-editor.css',
                 'css/vendor-overrides/editorjs.css',
                 'css/components/app-page-copy.css',