Phase 1: CKPool build infrastructure

Forks CKPool-solo at upstream commit cfb0f83b (v1.0) via a multi-stage
Docker build, with an env-driven entrypoint that renders ckpool.conf from
a template. The pinned commit already includes every fix referenced in
Bassin issue #29 (workbase_id double increment, extended low-power
timeouts, configurable dropidle, vardiff burst handling).

No patches are applied yet — the patches/ directory holds the workflow
and build wiring so Kamado-specific patches can be added incrementally.

Build is portable across aarch64/x86_64: yasm is intentionally omitted
so CKPool falls back to its C SHA256, and CFLAGS override drops upstream's
default -march=native. Runtime image ships ckpool and ckpmsg for socket
debugging; share logging (-L) is enabled by default.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Makefile

@@ -0,0 +1,32 @@
+# ----------------------------------------------------------------------------
+# Kamado Pool — top-level Makefile
+# ----------------------------------------------------------------------------
+.PHONY: help ckpool ckpool-shell up down logs clean
+
+help:
+	@echo "Kamado Pool targets:"
+	@echo "  make ckpool        Build the ckpool-solo docker image"
+	@echo "  make ckpool-shell  Open a shell in the built ckpool image"
+	@echo "  make up            docker compose up -d"
+	@echo "  make down          docker compose down"
+	@echo "  make logs          Tail ckpool logs"
+	@echo "  make clean         Remove build artifacts and data"
+
+ckpool:
+	docker build -t kamado/ckpool:dev ./ckpool
+
+ckpool-shell: ckpool
+	docker run --rm -it --entrypoint /bin/sh kamado/ckpool:dev
+
+up:
+	docker compose up -d --build
+
+down:
+	docker compose down
+
+logs:
+	docker compose logs -f ckpool
+
+clean:
+	docker compose down -v || true
+	rm -rf data/ build/ dist/