Add bundled TTF fonts, page geometry, column allocator and render model

Static TTF fonts (IBM Plex Sans/Mono, Noto Devanagari/Kannada) with a
fontkit-generated manifest, a verifier and OFL licences. Every family
registers a normal and italic source so fallback stacks cannot throw.
Adds A4/Letter geometry with margin presets, an exact column allocator,
deterministic Indian-grouping money and date formatting, text sanitising
and a pure buildRenderModel.

src/lib/pdf.tsx

@@ -2,6 +2,7 @@ import { pdf } from "@react-pdf/renderer";
 import { save } from "@tauri-apps/plugin-dialog";
 import { registerPdfFonts } from "../pdf/fonts";
 import { InvoiceDocument, type InvoicePdfProps } from "../pdf/InvoiceDocument";
+import { bankFromSnapshot, vendorFromSnapshot } from "../pdf/model/vendor";
 import { api } from "./api";
 import type { BankAccount, Invoice, Settings } from "./types";
 
@@ -17,15 +18,6 @@ function blobToBase64(blob: Blob): Promise<string> {
   });
 }
 
-function vendorFromSnapshot(snapshot: string | undefined, live: Settings): Settings {
-  if (!snapshot) return live;
-  try {
-    return { ...live, ...(JSON.parse(snapshot) as Partial<Settings>) };
-  } catch {
-    return live;
-  }
-}
-
 export async function buildPdfProps(
   invoice: Invoice,
   settings: Settings,
@@ -39,14 +31,7 @@ export async function buildPdfProps(
     ? await api.readAssetDataUri(invoice.signaturePath)
     : null;
 
-  let resolvedBank = bank;
-  if (!resolvedBank && invoice.bankSnapshot) {
-    try {
-      resolvedBank = JSON.parse(invoice.bankSnapshot) as BankAccount;
-    } catch {
-      resolvedBank = null;
-    }
-  }
+  const resolvedBank = bankFromSnapshot(invoice.bankSnapshot, bank);
 
   return {
     vendor,