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/db/schema/decks.ts

@@ -0,0 +1,37 @@
+import { sql } from 'drizzle-orm';
+import { index, jsonb, text, timestamp } from 'drizzle-orm/pg-core';
+
+import { cardsSchema } from './_schema.ts';
+
+/**
+ * Decks — Sammlungen von Karten. Eine Karte gehört zu genau einem Deck.
+ * `fsrs_settings` ist ein JSONB-Slot für per-Deck-Overrides der globalen
+ * FSRS-Defaults (siehe @cards/domain `FsrsSettings`).
+ */
+export const decks = cardsSchema.table(
+	'decks',
+	{
+		id: text('id').primaryKey(),
+		userId: text('user_id').notNull(),
+		name: text('name').notNull(),
+		description: text('description'),
+		color: text('color'),
+		visibility: text('visibility', { enum: ['private', 'space', 'public'] })
+			.notNull()
+			.default('private'),
+		fsrsSettings: jsonb('fsrs_settings').notNull().default(sql`'{}'::jsonb`),
+		contentHash: text('content_hash'),
+		createdAt: timestamp('created_at', { withTimezone: true, mode: 'date' })
+			.notNull()
+			.defaultNow(),
+		updatedAt: timestamp('updated_at', { withTimezone: true, mode: 'date' })
+			.notNull()
+			.defaultNow(),
+	},
+	(t) => ({
+		userIdx: index('decks_user_idx').on(t.userId),
+	})
+);
+
+export type DeckRow = typeof decks.$inferSelect;
+export type DeckInsert = typeof decks.$inferInsert;