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/routes/admin/issued-orders.ts

@@ -21,8 +21,10 @@ import {
 import {
   renderIssuedOrderHtml,
   buildIssuedOrderPdfFooter,
+  buildIssuedOrderPdfHeader,
 } from "./issued-orders-pdf";
 import { htmlToPdf } from "../../utils/html-to-pdf";
+import { logoDataUriFromSettings } from "../../utils/pdf-shared";
 import { nasOrdersManager } from "../../services/nas-financials-manager";
 import { contentDisposition } from "../../utils/content-disposition";
 
@@ -310,6 +312,11 @@ export default async function issuedOrdersRoutes(fastify: FastifyInstance) {
           sections,
         );
         const pdf = await htmlToPdf(html, {
+          headerTemplate: buildIssuedOrderPdfHeader(
+            lang,
+            logoDataUriFromSettings(settings),
+            order.po_number || "",
+          ),
           footerTemplate: buildIssuedOrderPdfFooter(lang, issuer.name),
         });