feat: editable billing text on invoices

- Added billing_text column to invoices table (VARCHAR 500)
- Prisma migration: 20260323_add_billing_text
- Form field on invoice create page with placeholder
- PDF uses billing_text, falls back to default translation
- Stored on create and editable on draft invoices

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

src/admin/pages/InvoiceDetail.tsx

@@ -77,6 +77,7 @@ interface InvoiceForm {
   payment_method: string
   constant_symbol: string
   issued_by: string
+  billing_text: string
   notes: string
   bank_account_id: number | string
   bank_name: string
@@ -271,6 +272,7 @@ export default function InvoiceDetail() {
     payment_method: 'Příkazem',
     constant_symbol: '0308',
     issued_by: user?.fullName || '',
+    billing_text: '',
     notes: '',
     bank_account_id: '',
     bank_name: '',
@@ -855,6 +857,16 @@ export default function InvoiceDetail() {
                 </FormField>
               </div>
 
+              <FormField label="Text fakturace (na PDF)">
+                <input
+                  type="text"
+                  value={form.billing_text}
+                  onChange={(e) => setForm(prev => ({ ...prev, billing_text: e.target.value }))}
+                  className="admin-form-input"
+                  placeholder="Fakturujeme Vám za: (ponechte prázdné pro výchozí)"
+                />
+              </FormField>
+
               <div className="admin-form-row">
                 <FormField label="Datum vystavení" error={errors.issue_date} required>
                   <AdminDatePicker mode="date" value={form.issue_date} onChange={(val: string) => { setForm(prev => ({ ...prev, issue_date: val })); setErrors(prev => ({ ...prev, issue_date: '' })) }} />

src/routes/admin/invoices-pdf.ts

@@ -880,7 +880,7 @@ ${indentCSS}
   </div>
 
   <!-- Polozky -->
-  <div class="billing-label">${escapeHtml(t.billing)}</div>
+  <div class="billing-label">${escapeHtml(invoice.billing_text || t.billing)}</div>
   <table class="items">
     <thead>
       <tr>

src/schemas/invoices.schema.ts

@@ -27,6 +27,7 @@ export const CreateInvoiceSchema = z.object({
   due_date: z.string().nullish(),
   tax_date: z.string().nullish(),
   issued_by: z.string().nullish(),
+  billing_text: z.string().nullish(),
   notes: z.string().nullish(),
   internal_notes: z.string().nullish(),
   items: z.array(InvoiceItemSchema).optional(),

src/services/invoices.service.ts

@@ -251,6 +251,7 @@ export async function createInvoice(body: Record<string, any>) {
       due_date: body.due_date ? new Date(String(body.due_date)) : null,
       tax_date: body.tax_date ? new Date(String(body.tax_date)) : null,
       issued_by: body.issued_by ? String(body.issued_by) : null,
+      billing_text: body.billing_text ? String(body.billing_text) : null,
       notes: body.notes ? String(body.notes) : null,
       internal_notes: body.internal_notes ? String(body.internal_notes) : null,
     },
@@ -293,7 +294,7 @@ export async function updateInvoice(id: number, body: Record<string, any>) {
   // Only allow full editing in 'issued' state
   const isDraft = currentStatus === 'issued';
   if (isDraft) {
-    const strFields = ['currency', 'payment_method', 'constant_symbol', 'bank_name', 'bank_swift', 'bank_iban', 'bank_account', 'issued_by'];
+    const strFields = ['currency', 'payment_method', 'constant_symbol', 'bank_name', 'bank_swift', 'bank_iban', 'bank_account', 'issued_by', 'billing_text'];
     for (const f of strFields) {
       if (body[f] !== undefined) data[f] = body[f] ? String(body[f]) : null;
     }