Start Housecarl: the logo, the wordmark and the skeleton

Housecarl will be a firewall manager for nftables, built the way Jarl and
Steward are: housecarld (a daemon with a REST API and web UI), hc (the
CLI) and SQLite.

- The logo: a carved Nordic doorway in Jarl's blue (artwork/logo.svg),
  with a small version without the carvings, lighter on dark
  backgrounds. scripts/logo.py builds the web UI's copies and
  scripts/banner.py the README banner.
- The HOUSECARL wordmark in Jarl's and Steward's angular letters, with
  new H, O, U and C (assets/brand.js), and the UI's color tokens.
- housecarld and hc print their version; the Makefile, version package,
  AGENTS.md, CHANGELOG and the design sketch (docs/design.md).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Makefile

@@ -0,0 +1,69 @@
+# Housecarl build.
+#
+#   make              build bin/housecarld and bin/hc (and their bash completion)
+#   make test         vet, gofmt check and unit tests
+#   make logo         rebuild the web UI's logo and the README banner from artwork/
+#   make dist         static binaries for linux/amd64 and linux/arm64 in dist/
+#   make cli-dist     the CLI alone for Linux, macOS and Windows in dist/
+#                     (housecarl-cli-<version>-<os>-<arch>[.exe])
+#
+# Installing, the systemd unit and the Debian packages come with the daemon
+# (as in Steward's Makefile).
+
+VERSION ?= $(shell cat VERSION 2>/dev/null || echo 0.0.0-dev)
+# RELEASE_TAG marks a build of a release (the web UI then shows and links
+# the release rather than the commit): set when HEAD is tagged v$(VERSION)
+# and no tracked file is changed.
+RELEASE_TAG ?= $(shell t=v$(VERSION); git tag --points-at HEAD 2>/dev/null | grep -qx "$$t" && git diff --quiet HEAD 2>/dev/null && echo $$t)
+# DESCRIBE places other builds relative to the last tag ("3 commits after
+# v0.2.0-rc.1").
+DESCRIBE ?= $(shell git describe --tags --long --match 'v[0-9]*' --abbrev=12 HEAD 2>/dev/null)
+LDFLAGS := -s -w -X housecarl/internal/version.Version=$(VERSION) -X housecarl/internal/version.Tag=$(RELEASE_TAG) \
+	-X housecarl/internal/version.Describe=$(DESCRIBE)
+GOFLAGS := -trimpath
+export CGO_ENABLED := 0
+
+.PHONY: all build completion test vet logo dist cli-dist clean
+
+all: build
+
+build:
+	go build $(GOFLAGS) -ldflags '$(LDFLAGS)' -o bin/housecarld ./cmd/housecarld
+	go build $(GOFLAGS) -ldflags '$(LDFLAGS)' -o bin/hc ./cmd/hc
+	$(MAKE) --no-print-directory completion
+
+# Bash completion scripts, generated by the binaries themselves.
+completion:
+	@mkdir -p bin/completion
+	bin/hc completion bash > bin/completion/hc
+	bin/housecarld completion bash > bin/completion/housecarld
+
+vet:
+	go vet ./...
+	@test -z "$$(gofmt -l cmd internal)" || { echo "gofmt needed:"; gofmt -l cmd internal; exit 1; }
+
+test: vet
+	go test ./...
+
+logo:
+	python3 scripts/logo.py
+
+dist: build
+	for arch in amd64 arm64; do \
+		GOOS=linux GOARCH=$$arch go build $(GOFLAGS) -ldflags '$(LDFLAGS)' -o dist/housecarl-$(VERSION)-linux-$$arch/housecarld ./cmd/housecarld && \
+		GOOS=linux GOARCH=$$arch go build $(GOFLAGS) -ldflags '$(LDFLAGS)' -o dist/housecarl-$(VERSION)-linux-$$arch/hc ./cmd/hc && \
+		tar -C dist -czf dist/housecarl-$(VERSION)-linux-$$arch.tar.gz housecarl-$(VERSION)-linux-$$arch || exit 1; \
+	done
+
+# The platforms cli-dist builds the CLI for.
+CLI_PLATFORMS ?= linux/amd64 linux/arm64 darwin/amd64 darwin/arm64 windows/amd64 windows/arm64
+
+cli-dist:
+	@mkdir -p dist
+	for p in $(CLI_PLATFORMS); do \
+		os=$${p%/*} arch=$${p#*/} ext=; [ $$os = windows ] && ext=.exe; \
+		GOOS=$$os GOARCH=$$arch go build $(GOFLAGS) -ldflags '$(LDFLAGS)' -o dist/housecarl-cli-$(VERSION)-$$os-$$arch$$ext ./cmd/hc || exit 1; \
+	done
+
+clean:
+	rm -rf bin dist