feat: add price scraper with JSON-LD/meta/regex fallback

- Implement extractPrice() to extract price from HTML with three fallback methods:
  1. JSON-LD Product schema (json-ld)
  2. og:price:amount meta tag (meta)
  3. Euro symbol regex pattern (regex)
- Implement fetchAndExtractPrice() for fetching URLs and extracting prices
- Includes helper functions for parsing and normalizing price values
- Add comprehensive test suite with fixtures for each extraction method
- All tests passing (14/14)

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013gwc3aCiyQxmCWQke8RvEz

test/scraper.test.js

@@ -0,0 +1,50 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const { extractPrice, fetchAndExtractPrice } = require('../src/scraper');
+
+function loadFixture(name) {
+  return fs.readFileSync(path.join(__dirname, 'fixtures', name), 'utf8');
+}
+
+test('extractPrice reads price from JSON-LD Product offers', () => {
+  const result = extractPrice(loadFixture('json-ld.html'));
+  assert.deepEqual(result, { price: 19.99, method: 'json-ld' });
+});
+
+test('extractPrice reads price from og:price:amount meta tag', () => {
+  const result = extractPrice(loadFixture('meta-tag.html'));
+  assert.deepEqual(result, { price: 24.50, method: 'meta' });
+});
+
+test('extractPrice falls back to euro-amount regex in page text', () => {
+  const result = extractPrice(loadFixture('regex-fallback.html'));
+  assert.deepEqual(result, { price: 14.95, method: 'regex' });
+});
+
+test('extractPrice returns null price when nothing matches', () => {
+  const result = extractPrice(loadFixture('no-price.html'));
+  assert.deepEqual(result, { price: null, method: null });
+});
+
+test('fetchAndExtractPrice returns error when fetch rejects', async () => {
+  const fetchImpl = async () => { throw new Error('network down'); };
+  const result = await fetchAndExtractPrice('https://example.invalid', { fetchImpl });
+  assert.equal(result.price, null);
+  assert.ok(result.error instanceof Error);
+});
+
+test('fetchAndExtractPrice returns error on non-OK response', async () => {
+  const fetchImpl = async () => ({ ok: false, status: 404, text: async () => '' });
+  const result = await fetchAndExtractPrice('https://example.invalid', { fetchImpl });
+  assert.equal(result.price, null);
+  assert.ok(result.error instanceof Error);
+});
+
+test('fetchAndExtractPrice extracts price from fetched HTML', async () => {
+  const html = loadFixture('meta-tag.html');
+  const fetchImpl = async () => ({ ok: true, status: 200, text: async () => html });
+  const result = await fetchAndExtractPrice('https://example.invalid', { fetchImpl });
+  assert.deepEqual(result, { price: 24.50, method: 'meta', error: null });
+});