Rename fmfuncs -> core (cleaner, semantic)

docs/SenSu 插件开发详细指南.md

@@ -542,7 +542,7 @@ import traceback
 
 # 导入框架装饰器
 try:
-    from fmfuncs.plugin_command_decorator import plugin_command, command
+    from core.plugin_command_decorator import plugin_command, command
 except ImportError:
     # 回退方案 - 本地定义装饰器
     def plugin_command(name=None, description=None, permissions=None):
@@ -5083,7 +5083,7 @@ logger.error("错误信息", exc_info=True)
 ### 9.1 PluginStatus 状态枚举
 
 ```python
-from fmfuncs.plugin_status import PluginStatus
+from core.plugin_status import PluginStatus
 
 # 插件生命周期状态
 PluginStatus.UNLOADED    # "unloaded"
@@ -5100,7 +5100,7 @@ PluginStatus.STOPPED     # "stopped"
 ### 9.2 PluginError 异常层级
 
 ```python
-from fmfuncs.plugin_error import (
+from core.plugin_error import (
     PluginError,            # 基础异常
     PluginLoadError,        # 加载失败
     PluginConfigError,      # 配置错误