Add typography roles, text primitives, fontkit measurer and layout lint

Txt always sets an absolute line height; RenderTxt never does. Row pins
every cell and stacks when the fill column would be too narrow. IdText and
FitText shrink then chunk or truncate. The fontkit measurer matches react-pdf
text widths exactly. A TypeScript-AST lint test enforces the layout rules
(no lineHeight outside Txt, no non-literal fixed/wrap/minPresenceAhead,
flexGrow needs flexBasis, no stray absolute positioning).

src/pdf/InvoiceDocument.test.tsx

@@ -4,7 +4,8 @@ import path from "node:path";
 import { beforeAll, describe, expect, it } from "vitest";
 import { InvoiceDocument, type InvoicePdfProps } from "./InvoiceDocument";
 import { registerPdfFonts } from "./fonts";
-import { describeBox, findOverlaps, renderPdfText, type RenderedPdf, type TextBox } from "./testing/pdfText";
+import { assertNoOverlap } from "./testing/asserts";
+import { describeBox, renderPdfText, type RenderedPdf, type TextBox } from "./testing/pdfText";
 import type { BankAccount, InvoiceItem, Settings } from "../lib/types";
 
 registerPdfFonts(path.resolve(process.cwd(), "public/fonts"));
@@ -146,12 +147,10 @@ const textOf = (items: TextBox[]) => items.map((t) => t.str).join(" ");
 function checkCommon(pdf: RenderedPdf) {
   const n = pdf.pages.length;
   expect(pdf.raw).not.toContain("/BaseFont /Helvetica");
+  assertNoOverlap(pdf.pages);
 
   pdf.pages.forEach((page, idx) => {
     const k = idx + 1;
-    const overlaps = findOverlaps(page).map(([a, b]) => `${describeBox(a)} x ${describeBox(b)}`);
-    expect(overlaps, `page ${k} overlaps`).toEqual([]);
-
     for (const t of page.items) {
       const isFooter = t.top > 780;
       expect(t.x0, `page ${k} ${describeBox(t)} left`).toBeGreaterThanOrEqual(MARGIN_L);