feat(api): URL-Kontext auch in /decks/generate + fetchUrlContent extrahieren

- `lib/url-fetch.ts`: fetchUrlContent aus decks-from-image herausgezogen
  — gemeinsam genutzte Logik für mana-search + direktes HTTP-Fetch-Fallback
- `decks-generate.ts`: optionales `url`-Feld im Input-Schema;
  URL-Inhalt wird an den Prompt angehängt wenn vorhanden
- `decks.ts` (web): `generateDeck()` akzeptiert jetzt `url?: string`
- UI: imageUrl wird für Text-KI + Bild-KI als Kontext genutzt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/api/src/lib/url-fetch.ts

@@ -0,0 +1,50 @@
+const MAX_URL_CHARS = 8_000;
+const MANA_SEARCH_URL = process.env.MANA_SEARCH_URL ?? 'http://localhost:3076';
+
+export async function fetchUrlContent(url: string): Promise<string | null> {
+	// Prefer mana-search (go-readability quality)
+	try {
+		const res = await fetch(`${MANA_SEARCH_URL}/api/v1/extract`, {
+			method: 'POST',
+			headers: { 'Content-Type': 'application/json' },
+			body: JSON.stringify({ url, options: { includeMarkdown: true, maxLength: MAX_URL_CHARS } }),
+			signal: AbortSignal.timeout(8_000),
+		});
+		if (res.ok) {
+			const data = await res.json() as {
+				success: boolean;
+				content?: { title?: string; markdown?: string; text?: string };
+			};
+			if (data.success && data.content) {
+				const text = data.content.markdown || data.content.text || '';
+				if (text.trim()) {
+					const title = data.content.title ? `# ${data.content.title}\n\n` : '';
+					return (title + text).slice(0, MAX_URL_CHARS);
+				}
+			}
+		}
+	} catch {
+		// mana-search nicht erreichbar — Fallback auf direktes Fetch
+	}
+
+	// Fallback: direktes HTTP-Fetch + einfaches HTML-Stripping
+	try {
+		const res = await fetch(url, {
+			headers: { 'User-Agent': 'Mozilla/5.0 (compatible; mana-cards/1.0; +https://cardecky.mana.how)' },
+			signal: AbortSignal.timeout(10_000),
+		});
+		if (!res.ok) return null;
+		const html = await res.text();
+		const text = html
+			.replace(/<script[^>]*>[\s\S]*?<\/script>/gi, ' ')
+			.replace(/<style[^>]*>[\s\S]*?<\/style>/gi, ' ')
+			.replace(/<[^>]+>/g, ' ')
+			.replace(/&amp;/g, '&').replace(/&lt;/g, '<').replace(/&gt;/g, '>').replace(/&nbsp;/g, ' ')
+			.replace(/&#?\w+;/g, ' ')
+			.replace(/\s+/g, ' ')
+			.trim();
+		return text ? text.slice(0, MAX_URL_CHARS) : null;
+	} catch {
+		return null;
+	}
+}