refactor: migrate API from Apollo Server to Mercurius and enhance GraphQL implementation

- Replaced Apollo Server with Mercurius for GraphQL API
- Updated resolvers to use Mercurius-compatible GraphQL implementation
- Migrated from Express to Fastify for server framework
- Improved error handling with GraphQL error extensions
- Added Zod for environment variable validation
- Updated Prisma schema and migrations
- Configured CORS and WebSocket subscriptions
- Simplified GraphQL schema and resolver structure
- Enhanced type safety and code organization

apps/api/prisma/migrations/20250306073430_init/migration.sql

@@ -0,0 +1,62 @@
+-- CreateTable
+CREATE TABLE `User` (
+    `id` VARCHAR(191) NOT NULL,
+    `email` VARCHAR(191) NOT NULL,
+    `username` VARCHAR(191) NOT NULL,
+    `password` VARCHAR(191) NOT NULL,
+    `createdAt` DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
+    `updatedAt` DATETIME(3) NOT NULL,
+
+    UNIQUE INDEX `User_email_key`(`email`),
+    UNIQUE INDEX `User_username_key`(`username`),
+    PRIMARY KEY (`id`)
+) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+
+-- CreateTable
+CREATE TABLE `Room` (
+    `id` VARCHAR(191) NOT NULL,
+    `name` VARCHAR(191) NOT NULL,
+    `description` VARCHAR(191) NULL,
+    `isPrivate` BOOLEAN NOT NULL DEFAULT false,
+    `createdAt` DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
+    `updatedAt` DATETIME(3) NOT NULL,
+    `ownerId` VARCHAR(191) NOT NULL,
+
+    PRIMARY KEY (`id`)
+) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+
+-- CreateTable
+CREATE TABLE `Message` (
+    `id` VARCHAR(191) NOT NULL,
+    `content` VARCHAR(191) NOT NULL,
+    `createdAt` DATETIME(3) NOT NULL DEFAULT CURRENT_TIMESTAMP(3),
+    `updatedAt` DATETIME(3) NOT NULL,
+    `userId` VARCHAR(191) NOT NULL,
+    `roomId` VARCHAR(191) NOT NULL,
+
+    PRIMARY KEY (`id`)
+) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+
+-- CreateTable
+CREATE TABLE `_RoomMembers` (
+    `A` VARCHAR(191) NOT NULL,
+    `B` VARCHAR(191) NOT NULL,
+
+    UNIQUE INDEX `_RoomMembers_AB_unique`(`A`, `B`),
+    INDEX `_RoomMembers_B_index`(`B`)
+) DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+
+-- AddForeignKey
+ALTER TABLE `Room` ADD CONSTRAINT `Room_ownerId_fkey` FOREIGN KEY (`ownerId`) REFERENCES `User`(`id`) ON DELETE RESTRICT ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE `Message` ADD CONSTRAINT `Message_userId_fkey` FOREIGN KEY (`userId`) REFERENCES `User`(`id`) ON DELETE RESTRICT ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE `Message` ADD CONSTRAINT `Message_roomId_fkey` FOREIGN KEY (`roomId`) REFERENCES `Room`(`id`) ON DELETE RESTRICT ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE `_RoomMembers` ADD CONSTRAINT `_RoomMembers_A_fkey` FOREIGN KEY (`A`) REFERENCES `Room`(`id`) ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE `_RoomMembers` ADD CONSTRAINT `_RoomMembers_B_fkey` FOREIGN KEY (`B`) REFERENCES `User`(`id`) ON DELETE CASCADE ON UPDATE CASCADE;