Update .env.example for all scripts

Co-authored-by: Cursor <cursoragent@cursor.com>

.env.example

@@ -1,9 +1,23 @@
-# Input PCB file (Protel 2.8 ASCII). Override with CLI: python3 capacitors_by_net_pair.py <file>
+# All scripts: set vars in .env or pass via CLI; CLI overrides .env.
+
+# Capacitors by net pair
 INPUT_FILE=board.pcb
-# Output JSON path. Override with: python3 capacitors_by_net_pair.py -o out.json
 OUTPUT_FILE=output/capacitors_by_net_pair.json
 
-# Compare locations: first and second Protel PCB file
+# Compare Protel locations
 FILE1=board_v1.pcb
 FILE2=board_v2.pcb
 COMPARE_OUTPUT=output/compare_locations.json
+THRESHOLD=1.0
+
+# Spreadsheet diff (designator column, data from row 10)
+SHEET1=sheet1.xlsx
+SHEET2=sheet2.xlsx
+DIFF_OUTPUT=output/spreadsheet_diff.json
+DESIGNATOR_COL=0
+START_ROW=9
+
+# Find bottom termination parts (search description column only; no package column)
+SHEET=sheet.xlsx
+BOTTOM_TERM_OUTPUT=output/bottom_termination_parts.json
+DESCRIPTION_COL=1