fix: 修复导出日期、语音和联系人名字问题

- 导出的 HTML：点月份先看日期，选中日期后才跳到对应消息。
- 语音转文字：不同账号、不同聊天里的语音不会再串到一起。
- 联系人名字：正常昵称显示不变；昵称异常时使用可见的备注或账号，导出文件名也能正常使用。

tests/unit/contact-name.test.ts

@@ -0,0 +1,36 @@
+import { describe, expect, it } from 'vitest'
+import {
+  displayContactName,
+  filesystemSafeName,
+  isVisibleName,
+  visibleNamePart
+} from '../../src/shared/contact-name'
+
+describe('contact name safety', () => {
+  it('recognizes private-use, zero-width, and control-only labels as invisible', () => {
+    expect(isVisibleName('\uE000\uE000')).toBe(false)
+    expect(isVisibleName('\u200B\u200D')).toBe(false)
+    expect(displayContactName({ m_nsNickName: '\uE000\uE000', remark: '备注名', wxid: 'wxid_a' })).toBe(
+      '备注名'
+    )
+  })
+
+  it('preserves visible emoji and removes only non-rendering code points', () => {
+    expect(visibleNamePart('  👩‍💻\u200B  ')).toBe('👩💻')
+    expect(
+      displayContactName({
+        m_nsNickName: String.fromCodePoint(0xE0020),
+        wechatId: 'wechat-alias'
+      })
+    ).toBe(
+      'wechat-alias'
+    )
+  })
+
+  it('sanitizes reserved path characters, trailing dots, device names, and length', () => {
+    expect(filesystemSafeName('a/b:c*?"<>|. ')).toMatch(/^a_b_c_+$/)
+    expect(filesystemSafeName('CON')).toBe('CON_')
+    expect(filesystemSafeName('\uE000\uE000', '未命名联系人')).toBe('未命名联系人')
+    expect(Array.from(filesystemSafeName('😀'.repeat(100))).length).toBe(80)
+  })
+})