Phase 3: Domain-Modell + Decks/Cards/Reviews-CRUD

Domain (@cards/domain):
- zod-Schemas SSOT für Deck, Card, Review, StudySession, FsrsSettings,
  Tools (cards.create + cards.search Input/Output)
- CardType-Discriminated-Union: MVP basic+basic-reverse, Future-Set
  (cloze, type-in, image-occlusion, audio, multiple-choice) für
  Schema-stable-Migration vorbereitet
- validateFieldsForType() Pure-Function pro CardType
- FSRS-Adapter über ts-fsrs v5.3.2: newReview, gradeReview,
  subIndexCount, toFsrsCard/fromFsrsCard ISO↔Date-Roundtrip
- Encryption-Hinweis: reviews bleiben PLAINTEXT (Scheduler quert
  täglich `due <= now`, siehe Lessons §3)

Drizzle-Schemas (apps/api/src/db/schema, alles in pgSchema('cards')):
- decks, cards, card_tags, reviews (PK card_id+sub_index), study_sessions,
  tags (deck-skopiert), media_refs (verweist auf mana-media), import_jobs
- _schema.ts-Pattern um Zirkular-Imports zu vermeiden (Lesson aus
  mana-share/-events während F-0)
- Hot-Path-Index reviews_user_due_idx für Scheduler-Queries

Routes (apps/api/src/routes):
- POST/GET/PATCH/DELETE /api/v1/decks (Deck-CRUD)
- POST/GET/PATCH/DELETE /api/v1/cards (Card-CRUD mit Auto-Reviews-Init:
  beim Card-Insert werden N Reviews via subIndexCount(type) angelegt,
  in einer Transaktion)
- GET /api/v1/reviews/due (Hot-Path, optional deck_id-Filter, Limit 500)
- POST /api/v1/reviews/:cardId/:subIndex/grade (FSRS-State-Transition,
  per-Deck FSRS-Settings)

Auth: Stub-Middleware liest X-User-Id-Header (Phase 2 ersetzt durch
@mana/shared-hono authMiddleware mit JWKS-Cache).

Tests (vitest, Hono app.request()):
- @cards/domain: fsrs.test.ts (newReview, gradeReview Roundtrip,
  Rating-Mapping), schemas.test.ts (zod-strict-Variants, Field-Type-
  Validation, hex-Color)
- apps/api: decks.test.ts + cards.test.ts + reviews.test.ts —
  Auth-Gate + Input-Validation. Volle DB-Integrationstests folgen mit
  pg-mem oder testcontainers in späterer Phase.

Cleanup: types.ts entfernt, zod-Schemas sind SSOT (z.infer für Types).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/api/src/lib/ulid.ts

@@ -0,0 +1,46 @@
+/**
+ * ULID-Generator (Crockford-Base-32).
+ * Bewusst lokal statt ulid-Lib, damit keine zusätzliche Abhängigkeit.
+ *
+ * 26 Zeichen: 10 Time + 16 Random.
+ * Lexikografisch sortierbar, monoton steigend.
+ */
+
+const CROCKFORD = '0123456789ABCDEFGHJKMNPQRSTVWXYZ';
+
+function randomBytes(n: number): Uint8Array {
+	const buf = new Uint8Array(n);
+	crypto.getRandomValues(buf);
+	return buf;
+}
+
+function encodeTime(now: number): string {
+	let s = '';
+	let n = now;
+	for (let i = 0; i < 10; i++) {
+		const r = n % 32;
+		s = CROCKFORD[r] + s;
+		n = Math.floor(n / 32);
+	}
+	return s;
+}
+
+function encodeRandom(): string {
+	const bytes = randomBytes(10);
+	let bits = 0;
+	let acc = 0;
+	let s = '';
+	for (const b of bytes) {
+		acc = (acc << 8) | b;
+		bits += 8;
+		while (bits >= 5) {
+			bits -= 5;
+			s += CROCKFORD[(acc >> bits) & 0x1f];
+		}
+	}
+	return s;
+}
+
+export function ulid(now: number = Date.now()): string {
+	return encodeTime(now) + encodeRandom();
+}