Add mobile expenses and receipt OCR

lib/receipt-ocr.ts

@@ -0,0 +1,50 @@
+import { isSupported, recognizeText } from "expo-mlkit-ocr";
+
+import { parseReceiptText, type ReceiptParseResult } from "@/lib/receipt-parse";
+
+export type ReceiptOcrResult = ReceiptParseResult & {
+  rawText: string;
+};
+
+export function mlKitOcrAvailable(): boolean {
+  try {
+    return isSupported();
+  } catch {
+    return false;
+  }
+}
+
+function normalizeImageUri(uri: string): string {
+  if (uri.startsWith("file://") || uri.startsWith("content://")) {
+    return uri;
+  }
+  return `file://${uri}`;
+}
+
+/** Run on-device ML Kit OCR and parse receipt fields from recognized text. */
+export async function recognizeReceiptFromImage(uri: string): Promise<ReceiptOcrResult> {
+  if (!mlKitOcrAvailable()) {
+    throw new Error("On-device OCR is not supported on this device.");
+  }
+
+  const result = await recognizeText(normalizeImageUri(uri));
+  const rawText = result.text?.trim() ?? "";
+  const parsed = parseReceiptText(rawText);
+
+  return {
+    ...parsed,
+    rawText,
+  };
+}
+
+export function applyReceiptOcrToForm(
+  ocr: ReceiptParseResult,
+  current: { description: string; amountText: string; date: Date },
+): { description: string; amountText: string; date: Date; ocrText: string } {
+  return {
+    description: ocr.vendor?.trim() || current.description,
+    amountText: ocr.amount != null ? String(ocr.amount) : current.amountText,
+    date: ocr.date ?? current.date,
+    ocrText: ocr.rawLines.join("\n"),
+  };
+}