refactor(shared-rss): extract RSS parsing + Readability into one package

news-ingester and apps/api both shipped their own copy of rss-parser
+ jsdom + Readability glue. Single source now in packages/shared-rss.
Adds discoverFeeds (rel=alternate + common-paths probe) and validateFeed
which News Research will use. JSDOM virtualConsole is silenced once,
in the package, instead of in two parallel call sites.

- packages/shared-rss: parse, extract, discover, validate
- services/news-ingester: drop local parsers, depend on @mana/shared-rss
- apps/api: drop @mozilla/readability + jsdom direct deps, use shared

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/shared-rss/src/parse.ts

@@ -0,0 +1,65 @@
+import Parser from 'rss-parser';
+import { DEFAULT_USER_AGENT, type NormalizedFeedItem } from './types';
+
+type CustomItem = {
+	'media:content'?: { $: { url: string } };
+	'media:thumbnail'?: { $: { url: string } };
+	enclosure?: { url?: string };
+};
+
+const parser: Parser<unknown, CustomItem> = new Parser({
+	timeout: 15_000,
+	headers: { 'User-Agent': DEFAULT_USER_AGENT },
+	customFields: {
+		item: ['media:content', 'media:thumbnail', 'enclosure'],
+	},
+});
+
+function mapItem(item: unknown): NormalizedFeedItem {
+	const i = item as CustomItem & {
+		link?: string;
+		title?: string;
+		content?: string;
+		contentSnippet?: string;
+		creator?: string;
+		author?: string;
+		isoDate?: string;
+	};
+
+	const imageUrl =
+		i['media:content']?.$?.url ?? i['media:thumbnail']?.$?.url ?? i.enclosure?.url ?? null;
+
+	return {
+		url: i.link ?? '',
+		title: i.title ?? '',
+		excerpt: i.contentSnippet ?? null,
+		content: i.contentSnippet ?? null,
+		htmlContent: i.content ?? null,
+		author: i.creator ?? i.author ?? null,
+		imageUrl,
+		publishedAt: i.isoDate ? new Date(i.isoDate) : null,
+	};
+}
+
+export async function parseFeedUrl(url: string): Promise<NormalizedFeedItem[]> {
+	const feed = await parser.parseURL(url);
+	return (feed.items ?? []).map(mapItem);
+}
+
+export async function parseFeedXml(xml: string): Promise<NormalizedFeedItem[]> {
+	const feed = await parser.parseString(xml);
+	return (feed.items ?? []).map(mapItem);
+}
+
+export interface ParsedFeed {
+	title: string | null;
+	items: NormalizedFeedItem[];
+}
+
+export async function parseFeedMeta(url: string): Promise<ParsedFeed> {
+	const feed = await parser.parseURL(url);
+	return {
+		title: feed.title ?? null,
+		items: (feed.items ?? []).map(mapItem),
+	};
+}