feat(tools/basic): 内置基础工具（calculator(注入安全)/datetime/random/text/json/markdown）+ 批量注册

plugins/tools/basic/doc.go

@@ -0,0 +1,9 @@
+// Package basic implements the built-in foundation tools for Cyrene v2
+// (DevDocs/design/09-插件生态.md, DevDocs/开发时间线.md M5): calculator,
+// datetime, random, text, json and markdown.
+//
+// Each tool is an sdk.Tool that is registered through the capability registry
+// via Register, and all of them are stateless values, so they are safe for
+// concurrent use. The tools are pure — no I/O and no network — so they can be
+// invoked from any role, any mode and any channel without sandboxing.
+package basic