feat: REST API v1 + API key management + Swagger docs

**API system**
- ApiKey model: SHA-256-hashed tokens (gw_<hex>), per-family, scoped
- Migration: 20260615210000_api_keys
- src/lib/api-auth.ts: verifyApiKey(), hasScope(), generateApiKey(), prepareKey()

**V1 endpoints** (all require Bearer gw_ token):
- GET  /api/v1/babies              — list family babies (any read scope)
- GET  /api/v1/events              — query events (events:read), babyId/type/from/to/limit/offset
- POST /api/v1/events              — log event (events:write), full metadata support
- GET  /api/v1/growth              — growth logs (growth:read)
- POST /api/v1/growth              — add measurement (growth:write), weight in grams
- GET  /api/v1/summary             — today's counts + sleep + last feed (summary:read)
- GET  /api/v1/milk                — stock lots + totalMl (milk:read)

**API key management**
- GET  /api/api-keys               — list keys (session auth)
- POST /api/api-keys               — create key, returns raw token once (session auth)
- DELETE /api/api-keys/[id]        — revoke key (session auth)

**Documentation**
- GET /api/v1/openapi.json         — OpenAPI 3.0 spec (CORS open)
- GET /api-docs                    — Swagger UI (CDN, dark themed)

**Settings UI** — "Clés API" section: create key with scope checkboxes, copy token banner (shown once), revoke, link to /api-docs

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

prisma/migrations/20260615210000_api_keys/migration.sql

@@ -0,0 +1,19 @@
+-- CreateTable
+CREATE TABLE "ApiKey" (
+    "id" TEXT NOT NULL,
+    "familyId" TEXT NOT NULL,
+    "name" TEXT NOT NULL,
+    "keyHash" TEXT NOT NULL,
+    "keyPrefix" TEXT NOT NULL,
+    "scopes" TEXT[],
+    "lastUsedAt" TIMESTAMP(3),
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "ApiKey_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "ApiKey_keyHash_key" ON "ApiKey"("keyHash");
+
+-- AddForeignKey
+ALTER TABLE "ApiKey" ADD CONSTRAINT "ApiKey_familyId_fkey" FOREIGN KEY ("familyId") REFERENCES "Family"("id") ON DELETE CASCADE ON UPDATE CASCADE;

prisma/schema.prisma

@@ -91,12 +91,25 @@ model Family {
   users                User[]
   babies               Baby[]
   eventTemplates       EventTemplate[]
+  apiKeys              ApiKey[]
   pinnedNote           String?
   pinnedNoteUpdatedAt  DateTime?
   pinnedNoteAuthor     String?
   createdAt            DateTime        @default(now())
 }
 
+model ApiKey {
+  id         String    @id @default(cuid())
+  familyId   String
+  family     Family    @relation(fields: [familyId], references: [id], onDelete: Cascade)
+  name       String
+  keyHash    String    @unique
+  keyPrefix  String
+  scopes     String[]
+  lastUsedAt DateTime?
+  createdAt  DateTime  @default(now())
+}
+
 model EventTemplate {
   id        String    @id @default(cuid())
   familyId  String