main: 初始化项目基础结构

- 添加项目必要的配置文件（例如 `.env.example`、`.gitignore` 等）
- 配置 Docker 环境相关文件（如 `.dockerignore`）
- 引入默认的 `composer.json` 依赖项和脚本配置
- 添加基础数据库迁移文件
- 配置 Laravel 默认的资源文件夹和初始内容

docker/app/Dockerfile

@@ -0,0 +1,26 @@
+FROM dunglas/frankenphp:1-php8.3
+
+WORKDIR /app
+
+# System packages and PHP extensions required by Laravel/Octane
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends \
+      git \
+      unzip \
+      libzip-dev \
+      libpq-dev \
+      zlib1g-dev \
+    && docker-php-ext-install \
+      pcntl \
+      zip \
+      pdo_mysql \
+      pdo_pgsql \
+    && pecl install redis \
+    && docker-php-ext-enable redis \
+    && rm -rf /var/lib/apt/lists/*
+
+# Composer for dependency management
+COPY --from=composer:2 /usr/bin/composer /usr/local/bin/composer
+
+# Default runtime command uses Octane (overridden by docker-compose entrypoint)
+CMD ["php", "artisan", "octane:start", "--server=frankenphp", "--host=0.0.0.0", "--port=8000"]