fix: auto-reply not triggering when source_prefix is empty (#880)

* fix: auto-reply not triggering when source_prefix is empty (#459)

- Empty source_prefix now matches all senders (was short-circuiting as falsy)
- Support regex matching with /pattern/ syntax in source_prefix
- Backward compatible: plain strings still use startsWith
- Use E2E_TEST_MODE switch to skip cloudflare:email import in tests
- Track reply() calls in E2E mock for testability

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: update auto-reply UI labels for regex support

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* docs: update changelogs for auto-reply fix and regex feature

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: upgrade version to v1.5.0

- Update version number to 1.5.0 in all package.json files and constants.ts
- Split CHANGELOG: v1.4.0 entries finalized, new v1.5.0(main) section with auto-reply changes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: add error logging for invalid regex in auto-reply source_prefix

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor: address CodeRabbit review suggestions

- Use const object instead of let for mock state tracking
- Add log when auto-reply subject/message falls back to defaults

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* docs: add source_prefix regex syntax to auto-reply docs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -6,7 +6,23 @@
   <a href="CHANGELOG_EN.md">🇺🇸 English</a>
 </p>
 
-## v1.4.0(main)
+## v1.5.0(main)
+
+### Features
+
+- feat: |自动回复| 发件人过滤支持正则表达式匹配，使用 `/pattern/` 语法（如 `/@example\.com$/`），同时保持前缀匹配的向后兼容
+
+### Bug Fixes
+
+- fix: |自动回复| 修复 `source_prefix` 为空字符串时自动回复不触发的问题（#459），空值现在正确匹配所有发件人
+
+### Testing
+
+- test: |E2E| 新增自动回复触发 E2E 测试，覆盖空前缀、前缀匹配、正则匹配和禁用状态场景
+
+### Improvements
+
+## v1.4.0
 
 ### Features