build(make): release target + expand SDK_DOWNSTREAM_DIRS

- `make release VERSION=vX.Y.Z` checks the tree is clean, pushes HEAD,
  tags, pushes the tag, then runs update-sdk so every downstream repo's
  go.mod gets bumped in one shot.
- SDK_DOWNSTREAM_DIRS now includes orchestrator/backend and
  blockninja-themes/* (globbed), which were both missing previously.

Makefile

@@ -3,6 +3,8 @@ SDK_VERSION ?= $(shell git describe --tags --abbrev=0)
 
 SDK_DOWNSTREAM_DIRS := \
 	$(HOME)/src/blockninja/backend \
+	$(HOME)/src/orchestrator/backend \
+	$(wildcard $(HOME)/src/blockninja-themes/*) \
 	$(HOME)/src/assumechaos \
 	$(HOME)/src/bidbuddy \
 	$(HOME)/src/bidmasters \
@@ -11,6 +13,10 @@ SDK_DOWNSTREAM_DIRS := \
 	$(HOME)/src/perthplaygrounds \
 	$(HOME)/src/symposium
 
+.PHONY: install-ninja
+install-ninja:
+	go install ./cmd/ninja
+
 .PHONY: update-sdk
 update-sdk:
 	@set -e; \
@@ -32,6 +38,20 @@ update-sdk:
 		); \
 	done
 
+# Tag + push a new SDK release, then bump the pin in every downstream repo.
+# Usage: make release VERSION=v0.11.0
+.PHONY: release
+release:
+	@if [ -z "$(VERSION)" ]; then echo "usage: make release VERSION=vX.Y.Z" >&2; exit 1; fi
+	@case "$(VERSION)" in v[0-9]*.[0-9]*.[0-9]*) ;; *) echo "VERSION must look like vX.Y.Z (got $(VERSION))" >&2; exit 1 ;; esac
+	@if ! git diff-index --quiet HEAD --; then echo "working tree dirty; commit before releasing" >&2; exit 1; fi
+	git push origin HEAD
+	git tag -a "$(VERSION)" -m "release $(VERSION)"
+	git push origin "$(VERSION)"
+	$(MAKE) update-sdk SDK_VERSION=$(VERSION)
+	@echo "==> $(VERSION) tagged + pushed; downstream go.mod files bumped."
+	@echo "    Review each downstream and commit the pin bump."
+
 .PHONY: check-sdk-pins
 check-sdk-pins:
 	@set -e; \