Makefile: fix help output and annotated release tags

- fix `make help` printing "Makefile" instead of target names — caused by
  `include tools.versions` adding to MAKEFILE_LIST; grep now targets Makefile directly
- `make release` now creates annotated tags: pre-populates the message
  with commits since the previous tag and opens $EDITOR for review

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

Makefile

@@ -9,7 +9,7 @@ CMD_PATH     := ./cmd/app
 
 # ── Default target ─────────────────────────────────────────────────────────────
 help: ## Show this help message
-	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | \
+	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' Makefile | \
 		awk 'BEGIN {FS = ":.*?## "}; {printf "  \033[36m%-16s\033[0m %s\n", $$1, $$2}' | sort
 
 # ── First-time setup ───────────────────────────────────────────────────────────
@@ -82,7 +82,18 @@ ifdef VERSION
 	$(MAKE) test-race
 	$(MAKE) lint
 	$(MAKE) security
-	git tag $(VERSION)
+	@MSG=$$(mktemp); \
+	LAST=$$(git describe --tags --abbrev=0 2>/dev/null); \
+	echo "$(VERSION)" > $$MSG; \
+	echo "" >> $$MSG; \
+	if [ -n "$$LAST" ]; then \
+		echo "Changes since $$LAST:" >> $$MSG; \
+		git log $$LAST..HEAD --oneline >> $$MSG; \
+	else \
+		git log --oneline >> $$MSG; \
+	fi; \
+	git tag -a -e -F $$MSG $(VERSION); \
+	rm -f $$MSG
 	git push origin $(VERSION)
 else
 	@echo "Released versions:"