Parse CSV and Filter

Context. Parse a CSV of orders, then keep only the ones above a threshold amount.

Your task. Write parse_and_filter(csv_text, min_amount) that parses the CSV and returns only rows where amount >= min_amount.

Example. CSV of 4 orders with amounts [100, 30, 75, 10], min_amount=50 → rows with 100 and 75.

Notes. Preserve row order from the CSV. min_amount higher than every value → empty DataFrame.