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__/accounts.test.ts

@@ -0,0 +1,54 @@
+import { afterEach, describe, expect, test } from 'bun:test'
+import { mkdtempSync, rmSync, statSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+
+const testDir = mkdtempSync(join(tmpdir(), 'weixin-test-accounts-'))
+process.env.WEIXIN_STATE_DIR = testDir
+
+import { clearAccount, loadAccount, saveAccount } from '../accounts.js'
+
+afterEach(() => {
+  rmSync(testDir, { recursive: true, force: true })
+})
+
+describe('account storage', () => {
+  test('loadAccount returns null when no account exists', () => {
+    expect(loadAccount()).toBeNull()
+  })
+
+  test('saveAccount and loadAccount round-trip', () => {
+    const data = {
+      token: 'test-token',
+      baseUrl: 'https://example.com',
+      userId: 'user1',
+      savedAt: '2025-01-01T00:00:00.000Z',
+    }
+    saveAccount(data)
+    expect(loadAccount()).toEqual(data)
+  })
+
+  test('saveAccount sets file permissions to 0600', () => {
+    saveAccount({
+      token: 'test',
+      baseUrl: 'https://example.com',
+      savedAt: new Date().toISOString(),
+    })
+    const stats = statSync(join(testDir, 'account.json'))
+    if (process.platform === 'win32') {
+      expect(stats.isFile()).toBe(true)
+      return
+    }
+    expect(stats.mode & 0o777).toBe(0o600)
+  })
+
+  test('clearAccount removes the file', () => {
+    saveAccount({
+      token: 'test',
+      baseUrl: 'https://example.com',
+      savedAt: new Date().toISOString(),
+    })
+    clearAccount()
+    expect(loadAccount()).toBeNull()
+  })
+})