Replace combined 'customer-address' with 4 separate elements:
- customer-street (Straße)
- customer-house-number (Hausnummer)
- customer-postal-code (PLZ)
- customer-city (Ort)
Update starter layout to use new separate fields with appropriate positioning.
The frontend was using /admin/invoice-template but the backend
endpoints are at /api/session/invoice-template. This caused 404
errors and the misleading message 'Template-Speicherung ist auf
diesem Server nicht verfuegbar'.
Remove the 'Steuerhinweis' (invoice-tax-note) element with the text
'* Alle Preise verstehen sich zzgl. gesetzlicher MwSt.' from:
- INVOICE_PALETTE_ITEMS list
- INVOICE_LOCKED_TEXT_PALETTE_IDS set
- Starter layout and adjust positions of following elements
Remove the unused invoice items elements from the admin invoice template:
- Remove 'invoice-items-header' and 'invoice-items-rows' palette items
- Remove 'Positionen' category from palette groups
- Remove these elements from the starter layout
- Remove IDs from INVOICE_LOCKED_TEXT_PALETTE_IDS
When no template was saved yet, the API returns 404. This does not mean
the API is unavailable - it just means no template exists yet. The code
was incorrectly setting isTemplateApiAvailable to false on 404, causing
the misleading message 'Template-API auf diesem Server nicht verfuegbar'.
Fixed in both InvoiceTemplatePage and ReportTemplatePage.
- Add 'Rechnung' menu with sub-items 'Verwalten' and 'Template' in admin sidebar
- Create InvoiceTemplatePage with drag-and-drop editor for invoice templates
- Includes invoice-specific elements (header, customer data, issuer info,
invoice items, totals, payment terms, bank details)
- Supports PDF preview and download
- API integration for saving/loading templates (/admin/invoice-template)
- Create InvoiceManagementPage as placeholder for invoice overview
- Add routes for /admin/rechnung/verwalten and /admin/rechnung/template
- Update page titles in AppShell for new routes
