Tune Myspace semantic aliases for student search intent

[SahilKumar75]

Summary

Improve Myspace search recall by tuning semantic aliases for student language, subject names, screenshots, classroom references, and study material cues.

Scope

• Review the current Myspace retrieval alias maps.
• Add aliases for common student search phrases such as notes, assignment, lab, timetable, board, lecture, and subject shortcuts.
• Add tests for alias-driven search matches and explanation labels.
• Keep the ranking deterministic.

Acceptance Criteria

• Alias changes improve recall without hiding exact matches.
• Tests cover at least three new search phrases.
• Result explanations show which alias category matched.
• The PR describes the tradeoff between recall and noisy matches.