Title: Implement minimal core framework with PL injection and update build config

Key features implemented:
- Updated package metadata and dependencies in PKG-INFO, setup files
- Added main.py entry point for backward compatibility with README launch method
- Enhanced CLI with config options, system info command, and proper signal handling
- Implemented minimal PluginManager loading only plugin-loader core plugin
- Refactored PluginLoader to follow minimal core design, removed sandbox/isolation complexity
- Updated auto-dependency plugin with safer PL injection mechanism and disabled pl_injection
- Removed legacy plugin files (firewall, frp_proxy, ftp_server, multi_lang_deploy, ops_toolbox, security_gateway) as functionality moved to core plugin system
- Improved gitignore with comprehensive ignore patterns

The changes implement a minimal core framework design where only the plugin-loader is directly loaded by the core, with all other plugins managed through the PL injection mechanism, significantly simplifying the architecture.

tests/test_plugin_loader.py

@@ -0,0 +1,48 @@
+"""插件加载器单元测试"""
+import pytest
+from pathlib import Path
+from oss.plugin.loader import PluginLoader
+
+
+class TestPluginLoader:
+    """测试插件加载器核心功能"""
+
+    def test_loader_initialization(self):
+        """测试加载器初始化"""
+        loader = PluginLoader()
+        assert loader.loaded == {}
+
+    def test_load_nonexistent_plugin(self):
+        """测试加载不存在的插件"""
+        loader = PluginLoader()
+        result = loader.load_core_plugin("nonexistent-plugin")
+        assert result is None
+
+    def test_load_plugin_loader(self):
+        """测试加载 plugin-loader 核心插件"""
+        loader = PluginLoader()
+        result = loader.load_core_plugin("plugin-loader")
+        
+        assert result is not None
+        assert "instance" in result
+        assert "module" in result
+        assert "path" in result
+        assert "name" in result
+        assert result["name"] == "plugin-loader"
+        assert hasattr(result["instance"], "init")
+        assert hasattr(result["instance"], "start")
+        assert hasattr(result["instance"], "stop")
+
+    def test_loaded_plugins_tracking(self):
+        """测试已加载插件跟踪"""
+        loader = PluginLoader()
+        initial_count = len(loader.loaded)
+        
+        loader.load_core_plugin("plugin-loader")
+        
+        assert len(loader.loaded) == initial_count + 1
+        assert "plugin-loader" in loader.loaded
+
+
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])