Rename scripts to capacitors, locations, bottom_termination; update README and .env

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

.env.example

@@ -1,12 +1,12 @@
 # All scripts: set vars in .env or pass via CLI; CLI overrides .env.
 
-# Capacitors by net pair
-INPUT_FILE=board.pcb
+# Capacitors by net pair (KiCad .kicad_pcb only)
+INPUT_FILE=board.kicad_pcb
 OUTPUT_FILE=outputs/capacitors_by_net_pair.json
 
-# Compare Protel locations
-FILE1=board_v1.pcb
-FILE2=board_v2.pcb
+# Compare KiCad locations (.kicad_pcb)
+FILE1=board_v1.kicad_pcb
+FILE2=board_v2.kicad_pcb
 COMPARE_OUTPUT=outputs/compare_locations.json
 THRESHOLD=1.0