feat(build): add makefile build script (#120)

Author: BrandonPacewic

Makefile

@@ -0,0 +1,63 @@
+# Copyright (c) Brandon Pacewic
+# SPDX‑License‑Identifier: MIT
+
+BUILD_DIR        ?= build
+CMAKE_GENERATOR  ?= Unix Makefiles
+BUILD_TESTS      ?= ON        # pass BUILD_TESTS=OFF to skip
+BUILD_BENCH      ?= OFF
+BUILD_TOOLS      ?= OFF
+BUILD_TYPE       ?= Debug     # Release | RelWithDebInfo ...
+JOBS             ?= $(shell nproc 2>/dev/null || sysctl -n hw.ncpu)
+
+CMAKE_FLAGS = \
+  -G "$(CMAKE_GENERATOR)" \
+  -DCMAKE_BUILD_TYPE=$(BUILD_TYPE) \
+  -DBUILD_TESTING=$(BUILD_TESTS) \
+  -DBUILD_BENCHMARKS=$(BUILD_BENCH) \
+  -DBUILD_TOOLS=$(BUILD_TOOLS) \
+
+.PHONY: build test bench tools \
+        format clean distclean help
+
+configure:
+	@mkdir -p "$(BUILD_DIR)"
+	@cmake -S . -B "$(BUILD_DIR)" $(CMAKE_FLAGS)
+
+build: configure
+	@cmake --build "$(BUILD_DIR)" -- -j$(JOBS)
+
+test: build
+	@ctest --test-dir "$(BUILD_DIR)" --output-on-failure
+
+bench: BUILD_BENCH := ON
+bench: build
+	@cmake --build "$(BUILD_DIR)" -j$(JOBS)
+
+tools: BUILD_TOOLS := ON
+tools: build
+
+format:
+	@clang-format -i -style=file $(shell git ls-files '*.hpp' '*.h' '*.cpp')
+
+clean:
+	@cmake --build "$(BUILD_DIR)" --target clean || true
+
+distclean:
+	@rm -rf "$(BUILD_DIR)"
+
+help:
+	@echo "Targets:"
+	@echo "  build              - configure and build"
+	@echo "  test               - run ctest (RUN_TESTS=ON)"
+	@echo "  bench              - build & run benchmarks (BUILD_BENCH=ON)"
+	@echo "  tools              - build project-defined tools (BUILD_TOOLS=ON)"
+	@echo "  format             - run clang-format on all source files"
+	@echo "  clean              - clean build artefacts"
+	@echo "  distclean          - clean entire build dir"
+	@echo ""
+	@echo "Knobs (override with VAR=value):"
+	@echo "  BUILD_DIR, CMAKE_GENERATOR, BUILD_TYPE, JOBS"
+	@echo "  BUILD_TESTS, BUILD_BENCH, BUILD_TOOLS"
+
+# Default to help when running `make` without targets
+.DEFAULT_GOAL := help