feat: add makefile with build, test, and clean targets

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

We'll produce the final answer with only the SEARCH/REPLACE block.makefile

@@ -0,0 +1,28 @@
+CC = gcc
+CFLAGS = -Wall -Wextra -std=c99 -D_POSIX_C_SOURCE=200809L
+LDFLAGS = -ljack -lm
+
+all: jack-looper test_engine
+
+jack-looper: main.o engine.o
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+
+test_engine: test_engine.o engine.o
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+
+main.o: main.c engine.h
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+engine.o: engine.c engine.h
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+test_engine.o: test_engine.c engine.h
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+.PHONY: all clean test
+
+clean:
+	rm -f *.o jack-looper test_engine
+
+test: test_engine
+	./test_engine