Refactor plugin loader and runner to support enhanced manifest structure

- Updated the PluginMeta class to utilize a strongly typed PluginManifest, improving type safety and clarity.
- Refactored dependency extraction logic to streamline the handling of plugin dependencies.
- Modified the PluginLoader to accommodate new manifest versioning and validation processes.
- Enhanced the PluginRunner to work with a dictionary for external available plugins, allowing for version mapping.
- Updated built-in plugins' manifest files to version 2, adding URLs and SDK versioning for better integration and documentation.
- Improved error handling and logging for plugin loading and dependency resolution processes.

src/plugin_runtime/__init__.py

@@ -18,7 +18,7 @@ ENV_HOST_VERSION = "MAIBOT_HOST_VERSION"
 """Runner 读取的 Host 应用版本号，用于 manifest 兼容性校验"""
 
 ENV_EXTERNAL_PLUGIN_IDS = "MAIBOT_EXTERNAL_PLUGIN_IDS"
-"""Runner 启动时可视为已满足的外部插件依赖列表（JSON 数组）"""
+"""Runner 启动时可视为已满足的外部插件依赖版本映射（JSON 对象）"""
 
 ENV_GLOBAL_CONFIG_SNAPSHOT = "MAIBOT_GLOBAL_CONFIG_SNAPSHOT"
 """Runner 启动时注入的全局配置快照（JSON 对象）"""