ILLUSTRATIVE SAMPLE — fictional or supplied example data.

Sample records
row_id,name,email
1,  Avery Chen  ,AVERY@example.test
2,Avery Chen,avery@example.test
3,Morgan Reed,
4,  Casey Park,Casey@example.test

Desired format
CSV columns row_id,name,email. Trim surrounding whitespace. Lowercase email. Deduplicate nonblank email case-insensitively, keeping the first row. Never discard a row just because email is blank. Keep row IDs. For this sample, expect 3 output rows and 1 duplicate removed. Generate a Python standard-library script that writes a NEW output file, refuses to overwrite an existing file, reports input/output/duplicate/blank-email counts, and shows how to run it. Never modify the source file.