Profiler: accept .tsv and .xlsx uploads in addition to .csv

[yakew7]

Summary

The profiler only handles comma-separated CSV. Support tab-separated (.tsv) and Excel (.xlsx).

Why

A lot of real health/admin data arrives as Excel or tab-delimited exports.

Tasks

• CLI: detect delimiter / read .xlsx via pandas (openpyxl optional extra)
• Web: delimiter sniffing in assets/profiler-engine.js; (.xlsx is harder client-side — scope/track separately)
• Tests for TSV parsing parity