feat: 接入 weixin 服务层与命令入口

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/services/weixin/__tests__/send.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, test } from 'bun:test'
+import { markdownToPlainText } from '../send.js'
+
+describe('markdownToPlainText', () => {
+  test('removes bold markers', () => {
+    expect(markdownToPlainText('**bold**')).toBe('bold')
+  })
+
+  test('removes italic markers', () => {
+    expect(markdownToPlainText('*italic*')).toBe('italic')
+  })
+
+  test('removes inline code backticks', () => {
+    expect(markdownToPlainText('`code`')).toBe('code')
+  })
+
+  test('removes code block fences', () => {
+    expect(markdownToPlainText("```js\nconsole.log('hi');\n```"))
+      .toBe("console.log('hi');")
+  })
+
+  test('converts links to text with URL', () => {
+    expect(markdownToPlainText('[click](https://example.com)')).toBe(
+      'click (https://example.com)',
+    )
+  })
+
+  test('handles mixed markdown', () => {
+    expect(markdownToPlainText('# Hello\n\n**bold** and *italic* with `code`'))
+      .toBe('Hello\n\nbold and italic with code')
+  })
+})