refactor: update binary name from lambda.exe to lambda

Changed BINARY_NAME from lambda.exe to lambda and updated all execution references to use the ${BINARY_NAME} variable.
Added lambda binary to .gitignore.

Makefile

@@ -1,4 +1,4 @@
-BINARY_NAME=lambda.exe
+BINARY_NAME=lambda
 TEST=simple
 
 .PHONY: help build run profile explain graph docs
@@ -19,13 +19,13 @@ build:
 	@ chmod +x ${BINARY_NAME}
 
 run: build
-	@ ./lambda.exe - < ./samples/$(TEST).txt > program.out
+	@ ./${BINARY_NAME} - < ./samples/$(TEST).txt > program.out
 
 profile: build
-	@ ./lambda.exe -p profile/cpu.prof - < ./samples/$(TEST).txt > program.out
+	@ ./${BINARY_NAME} -p profile/cpu.prof - < ./samples/$(TEST).txt > program.out
 
 explain: build
-	@ ./lambda.exe -x -p profile/cpu.prof - < ./samples/$(TEST).txt > program.out
+	@ ./${BINARY_NAME} -x -p profile/cpu.prof - < ./samples/$(TEST).txt > program.out
 
 graph:
 	@ go tool pprof -raw -output=profile/cpu.raw profile/cpu.prof