fix: make default target print help instead of building

ober

f899584f2052b879125364decce9d0f38dd61c15

diff --git a/Makefile b/Makefile
index dbf9ef6..33b533a 100644
--- a/Makefile
+++ b/Makefile
@@ -7,7 +7,65 @@ CHEZ_EXT_LIBDIRS = $(CHEZ_EXT_DIR)/chez-https/src:$(CHEZ_EXT_DIR)/chez-ssl/src:$
 # Shared object paths for legacy FFI-based chez-* libraries
 CHEZ_EXT_LDPATH = $(CHEZ_EXT_DIR)/chez-ssl:$(CHEZ_EXT_DIR)/chez-zlib:$(CHEZ_EXT_DIR)/chez-pcre2:$(CHEZ_EXT_DIR)/chez-leveldb:$(CHEZ_EXT_DIR)/chez-epoll:$(CHEZ_EXT_DIR)/chez-inotify:$(CHEZ_EXT_DIR)/chez-crypto:$(CHEZ_EXT_DIR)/chez-sqlite:$(CHEZ_EXT_DIR)/chez-postgresql
 
-.PHONY: build test test-reader test-core test-runtime test-stdlib test-ffi test-modules test-expanded test-features test-wrappers test-phase4a test-phase4b test-phase4c test-phase4d test-phase4e test-phase4f test-phase5 test-phase5e test-phase6 test-phase7 test-phase8 test-functional test-repl test-security test-native test-gaps native clean-native audit-native clean fuzz fuzz-smoke fuzz-deep fuzz-reader-fuzz fuzz-json-fuzz fuzz-http2-fuzz fuzz-websocket-fuzz fuzz-dns-fuzz fuzz-pregexp-fuzz fuzz-csv-fuzz fuzz-base64-fuzz fuzz-hex-fuzz fuzz-uri-fuzz fuzz-format-fuzz fuzz-router-fuzz fuzz-sandbox-fuzz test-rawstring test-regex test-rx test-peg test-regex-all docker-build docker-push
+.PHONY: help build test test-reader test-core test-runtime test-stdlib test-ffi test-modules test-expanded test-features test-wrappers test-phase4a test-phase4b test-phase4c test-phase4d test-phase4e test-phase4f test-phase5 test-phase5e test-phase6 test-phase7 test-phase8 test-functional test-repl test-security test-native test-gaps native clean-native audit-native clean fuzz fuzz-smoke fuzz-deep fuzz-reader-fuzz fuzz-json-fuzz fuzz-http2-fuzz fuzz-websocket-fuzz fuzz-dns-fuzz fuzz-pregexp-fuzz fuzz-csv-fuzz fuzz-base64-fuzz fuzz-hex-fuzz fuzz-uri-fuzz fuzz-format-fuzz fuzz-router-fuzz fuzz-sandbox-fuzz test-rawstring test-regex test-rx test-peg test-regex-all docker-build docker-push
+
+help:
+	@echo "Usage: make <target>"
+	@echo ""
+	@echo "Build:"
+	@echo "  build            Compile all Jerboa libraries"
+	@echo "  native           Build Rust native library"
+	@echo "  clean            Remove compiled .so and .wpo artifacts"
+	@echo "  clean-native     Remove Rust build artifacts"
+	@echo "  audit-native     Run cargo audit on Rust native library"
+	@echo ""
+	@echo "Test (core):"
+	@echo "  test             Run core test suite (reader, stdlib, ffi, regex)"
+	@echo "  test-reader      Reader tests"
+	@echo "  test-core        Core language tests"
+	@echo "  test-runtime     Runtime tests"
+	@echo "  test-stdlib      Standard library tests"
+	@echo "  test-ffi         FFI tests"
+	@echo "  test-modules     Module system tests"
+	@echo "  test-expanded    Expanded stdlib tests"
+	@echo "  test-regex-all   All regex tests (rawstring, regex, rx, peg)"
+	@echo "  test-rawstring   Raw string reader tests"
+	@echo "  test-regex       Regex tests"
+	@echo "  test-rx          Rx pattern tests"
+	@echo "  test-peg         PEG grammar tests"
+	@echo "  test-repl        REPL tests"
+	@echo "  test-functional  Functional tests (I/O, fork, signals)"
+	@echo "  test-gaps        Gap coverage tests"
+	@echo ""
+	@echo "Test (features):"
+	@echo "  test-features    Phase 2 + Phase 3 feature tests"
+	@echo "  test-wrappers    FFI wrapper module tests"
+	@echo "  test-security    Security tests"
+	@echo "  test-native      Rust native library tests"
+	@echo "  test-all         All test suites combined"
+	@echo "  test-phase2      Phase 2 feature tests"
+	@echo "  test-phase3      Phase 3 feature tests"
+	@echo "  test-phase4a     Phase 4a: Core runtime tests"
+	@echo "  test-phase4b     Phase 4b: Type system and safety tests"
+	@echo "  test-phase4c     Phase 4c: Systems and performance tests"
+	@echo "  test-phase4d     Phase 4d: Developer experience tests"
+	@echo "  test-phase4e     Phase 4e: Data and distribution tests"
+	@echo "  test-phase4f     Phase 4f: Toolchain and interop tests"
+	@echo "  test-phase5      Phase 5: All sub-phases"
+	@echo "  test-phase5e     Phase 5e: Systems and zero-cost tests"
+	@echo "  test-phase6      Phase 6: Real programs tests"
+	@echo "  test-phase7      Phase 7: Gerbil porting features"
+	@echo "  test-phase8      Phase 8: Deep Gerbil compatibility"
+	@echo ""
+	@echo "Fuzzing:"
+	@echo "  fuzz             Run all fuzz harnesses (default iterations)"
+	@echo "  fuzz-smoke       Quick smoke fuzz for CI (~30s)"
+	@echo "  fuzz-deep        Long-running deep fuzz (nightly)"
+	@echo "  fuzz-<target>    Individual fuzz targets (reader, json, http2, ...)"
+	@echo ""
+	@echo "Docker:"
+	@echo "  docker-build     Build jerboa21/jerboa base image"
+	@echo "  docker-push      Push base image to Docker Hub"
 
 build:
 	$(SCHEME) --libdirs $(LIBDIRS) --script support/build.ss