feat(invoices)!: Obsah sections, internal-only notes, unified per-page PDF header+footer

Invoices now mirror the issued-orders document model:

- New invoice_sections table (CZ/EN rich-text "Obsah") edited via the
  shared SectionsEditor, printed inline right after the items on the
  PDF. Full-replace on update, same transaction as items.
- Printed notes dropped: the notes column is removed (migration merges
  existing content into internal_notes first); the form field is now
  "Interni poznamky", never printed. Legacy payloads sending notes are
  silently stripped.
- Form cleanup: Cislo faktury and Vystavil fields removed (number lives
  in the header, issued_by auto-fills); page header title restyled to
  the orders/offers pattern (number span + status chip).
- Unified per-page PDF header for the red-accent family: shared
  buildPdfHeaderTemplate in pdf-shared (22mm logo, red heading, red
  rule) rendered by a Puppeteer headerTemplate on EVERY page of both
  invoices and issued orders (incl. the /file fallback render); body
  headers are print-hidden. htmlToPdf gained the headerTemplate option.
- Footer parity: invoices get the per-page "Vystavil + Strana X z Y"
  footer; the invoice bottom block (notice + QR/VAT recap + Prevzal)
  is break-inside: avoid so a page break can never split it.
- @page margins now match the template space (32mm top, 18mm bottom) -
  Chromium lays out by CSS @page margins, which also fixes issued
  orders' content running into the 18mm footer zone on full pages.

BREAKING CHANGE: invoices.notes column dropped (data merged into
internal_notes); deploy must run prisma migrate deploy + generate.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/schemas/invoices.schema.ts

@@ -6,6 +6,7 @@ import {
   positiveNumberFromForm,
   nullableIntIdFromForm,
   booleanFromForm,
+  DocumentSectionSchema,
 } from "./common";
 
 const InvoiceItemSchema = z.object({
@@ -38,9 +39,14 @@ export const CreateInvoiceSchema = z.object({
   issued_by: z.string().max(255).nullish(),
   billing_text: z.string().max(8000).nullish(),
   language: z.string().max(20).optional().default("cs"),
-  notes: z.string().max(8000).nullish(),
+  // `notes` was dropped (printed-notes block removed — free-form PDF content
+  // lives in the sections); legacy clients still sending it are silently
+  // stripped by z.object. internal_notes is never printed.
   internal_notes: z.string().max(8000).nullish(),
   items: z.array(InvoiceItemSchema).optional(),
+  // Rich-text CZ/EN "Obsah" sections rendered after the items on the PDF
+  // (mirrors issued orders — shared DocumentSectionSchema, DB-aligned limits).
+  sections: z.array(DocumentSectionSchema).optional(),
 });
 
 export const UpdateInvoiceSchema = z.object({
@@ -61,10 +67,10 @@ export const UpdateInvoiceSchema = z.object({
   issue_date: z.union([z.string().max(255), z.null()]).optional(),
   due_date: z.union([z.string().max(255), z.null()]).optional(),
   tax_date: z.union([z.string().max(255), z.null()]).optional(),
-  notes: z.string().max(8000).nullish(),
   internal_notes: z.string().max(8000).nullish(),
   paid_date: z.union([z.string().max(255), z.null()]).optional(),
   items: z.array(InvoiceItemSchema).optional(),
+  sections: z.array(DocumentSectionSchema).optional(),
 });
 
 export type CreateInvoiceInput = z.infer<typeof CreateInvoiceSchema>;