main: 引入 AgentProvider 流式事件与 OpenAI 兼容适配

- 增加流式事件流支持，Provider 输出 `message.delta` 等事件
- 实现 OpenAI 兼容适配器，包括 RequestBuilder、ApiClient 等模块
- 更新 Agent Run 逻辑，支持流式增量写入与模型完成状态管理
- 扩展配置项 `agent.openai.*`，支持模型、密钥等配置
- 优化文档，完善流式事件与消息类型说明
- 增加单元测试，覆盖 Provider 和 OpenAI 适配相关逻辑
- 更新环境变量与配置示例，支持新功能

config/agent.php

@@ -8,9 +8,19 @@ return [
         'retry_times' => env('AGENT_PROVIDER_RETRY_TIMES', 1),
         'retry_backoff_ms' => env('AGENT_PROVIDER_RETRY_BACKOFF_MS', 500),
     ],
+    'openai' => [
+        'base_url' => env('AGENT_OPENAI_BASE_URL', 'https://api.openai.com/v1'),
+        'api_key' => env('AGENT_OPENAI_API_KEY', ''),
+        'organization' => env('AGENT_OPENAI_ORGANIZATION', ''),
+        'project' => env('AGENT_OPENAI_PROJECT', ''),
+        'model' => env('AGENT_OPENAI_MODEL', 'gpt-4o-mini'),
+        'temperature' => env('AGENT_OPENAI_TEMPERATURE', 0.7),
+        'top_p' => env('AGENT_OPENAI_TOP_P', 1.0),
+        'include_usage' => env('AGENT_OPENAI_INCLUDE_USAGE', false),
+    ],
     'job' => [
         'tries' => env('AGENT_RUN_JOB_TRIES', 1),
-        'backoff_seconds' => env('AGENT_RUN_JOB_BACKOFF', 5),
-        'timeout_seconds' => env('AGENT_RUN_JOB_TIMEOUT', 120),
+        'backoff_seconds' => env('AGENT_RUN_JOB_BACKOFF', 3),
+        'timeout_seconds' => env('AGENT_RUN_JOB_TIMEOUT', 360),
     ],
 ];