Initial commit: OTA chunk transfer protocol implementation

- Protocol definition with 6-byte header (chunk_idx: 2B, payload: N B, crc32: 4B)
- Node.js server with chunk-based HTTP delivery
- C client library with resumable download support
- CRC32 implementation (IEEE 802.3)
- Test suites for both server and CRC32
- 1024B default chunk size (0.59% overhead)

Makefile

@@ -0,0 +1,22 @@
+# OTA Chunk Transfer Makefile
+
+CC = gcc
+CFLAGS = -Wall -Wextra -std=c11 -I protocol
+LDFLAGS = 
+
+SRCS = protocol/crc32.c protocol/chunk_client.c
+OBJS = $(SRCS:.c=.o)
+
+.PHONY: all clean test
+
+all: $(OBJS)
+
+# CRC32 test
+test_crc32: tests/test_crc32.c protocol/crc32.c
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+
+test: test_crc32
+	./test_crc32
+
+clean:
+	rm -f *.o protocol/*.o tests/*.o test_crc32