api: API key authentication with rotation and grace period

- Add ApiKey Prisma model (keyHash, expiresAt, revokedAt)
- Protect /api/v1/* routes with Authorization: Bearer header check in hooks
- create rotateApiKey() utility: normal (48h grace) and emergency (immediate)
- Add Super-only /admin/api-keys page for key rotation with one-time reveal
- Fix roleId check by using parent layout's DB-fetched adminUser
- Add API Keys link to admin sidebar

prisma/migrations/20260708181143_add_api_key/migration.sql

@@ -0,0 +1,14 @@
+-- CreateTable
+CREATE TABLE "ApiKey" (
+    "id" TEXT NOT NULL,
+    "keyPrefix" TEXT NOT NULL,
+    "keyHash" TEXT NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "expiresAt" TIMESTAMP(3),
+    "revokedAt" TIMESTAMP(3),
+
+    CONSTRAINT "ApiKey_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "ApiKey_keyHash_key" ON "ApiKey"("keyHash");