docs: add TSV validation tip to program.md

[tykoo-chen]

Problem

AI agents sometimes write malformed TSV entries (wrong delimiter, missing columns, etc.) which breaks the analysis notebook.

Solution

Add a quick validation tip showing how to check the TSV format:

head -1 results.tsv  # Verify header
wc -l results.tsv    # Count experiments

Simple addition that helps catch formatting issues early.