ci: drive pipeline via make targets + local make ci gate (refs #30)

Add a root Makefile (lint/build/unit/smoke/ci) as the single source of
truth for the checks, and have each Gitea Actions job call the matching
make target so local and CI cannot drift. `make ci` runs the full
pipeline locally — the interim gate while no runner is registered.

The smoke target auto-points DOCKER_HOST at the rootless Podman socket
when present (and DOCKER_HOST is unset), leaving Docker/CI hosts alone.
Document `make ci` and the Podman prerequisites in docs/runbooks/ci.md.

Verified: `make ci` is green locally (lint, build, unit, container smoke).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Makefile

@@ -0,0 +1,50 @@
+# Developer + CI entrypoints.
+#
+# These targets are the single source of truth for the checks. The Gitea
+# Actions workflow (.gitea/workflows/ci.yaml) invokes the SAME targets, so
+# `make ci` locally runs exactly what the pipeline runs — no drift. Until a
+# self-hosted runner is registered, `make ci` is the gate (see docs/runbooks/ci.md).
+
+SLN        := services/bff/Bff.slnx
+COMPOSE    := infra/docker-compose.yml
+HEALTH_URL := http://localhost:8080/health
+
+# On a rootless Podman dev box, point Docker CLI/Compose at the Podman socket —
+# but only if that socket exists and DOCKER_HOST isn't already set, so real
+# Docker hosts and CI runners are left untouched.
+PODMAN_SOCK := /run/user/$(shell id -u)/podman/podman.sock
+ifeq ($(wildcard $(PODMAN_SOCK)),$(PODMAN_SOCK))
+ifeq ($(origin DOCKER_HOST),undefined)
+export DOCKER_HOST := unix://$(PODMAN_SOCK)
+endif
+endif
+
+.PHONY: ci lint build unit smoke down help
+
+## ci: run the full pipeline — lint, build, unit, smoke (mirrors Gitea Actions)
+ci: lint build unit smoke
+
+## lint: verify formatting (no changes)
+lint:
+	dotnet format $(SLN) --verify-no-changes
+
+## build: release build
+build:
+	dotnet build $(SLN) -c Release
+
+## unit: run unit tests
+unit:
+	dotnet test $(SLN) -c Release
+
+## smoke: compose up (wait for healthy), curl /health, then tear down
+smoke:
+	docker compose -f $(COMPOSE) up -d --build --wait
+	bash -c 'curl -fsS $(HEALTH_URL); rc=$$?; docker compose -f $(COMPOSE) down --volumes; exit $$rc'
+
+## down: stop and remove the local stack
+down:
+	docker compose -f $(COMPOSE) down --volumes
+
+## help: list available targets
+help:
+	@grep -E '^## ' $(MAKEFILE_LIST) | sed 's/^## //'