fix: reconcile HR, self, and system message direction

[shuaigechz-cloud]

Summary

• classify BOSS recommendation and account notices as system messages instead of HR replies
• use message class evidence for self, HR, and unknown direction rather than treating every non-self bubble as HR
• reconcile a saved greeting back to self when the DOM direction marker is missing
• keep unknown messages conservative and preserve explicit resume request cards

Why

The monitor is intended to react to HR replies, but chat rows and message bubbles can also contain BOSS platform notices or lose their direction marker after DOM changes. Treating every unmarked message as HR can create false reply records, unnecessary AI suggestions, or incorrect resume-request handling.

Tests

• 308 pytest tests passed
• 14 subtests passed
• monitor suite: 11 tests and 9 subtests passed
• Python compile check passed with SyntaxWarning treated as an error

Validation boundary

• no live BOSS conversation was opened or modified while preparing this PR
• no automatic reply, follow-up, resume send, or application action was performed
• no resume, database, API credential, log, screenshot, generated output, local path, or personal contact information is included

[powerycy]

该消息方向修复已纳入 PR #62：区分 HR、本人及 BOSS 系统通知，避免误触发监测处理。已与 PR #63 的监测风控一起完成全量回归。此 PR 由 #62 取代，现关闭。

[powerycy]

最终状态：HR、本人和 BOSS 系统消息方向识别已通过 #62 合并到 main，平台系统通知不会再被当作 HR 回复。最终整合回归与 CI 均通过，贡献已列入 #74。