Add release infrastructure and complete implementation

- Dockerfile: distroless container for MCP server
- GoReleaser: multi-platform binary and Docker builds with cosign signing
- GitHub Actions: release workflow using shared actions
- Semver config for automatic version calculation
- Persistence layer, content indexing, and improved tool handlers

Makefile

@@ -0,0 +1,17 @@
+BINARY := compactor
+BUILDFLAGS := -buildvcs=false -trimpath
+
+.PHONY: build clean test lint
+
+build:
+	go build $(BUILDFLAGS) -o $(BINARY) .
+
+clean:
+	rm -f $(BINARY)
+
+test:
+	go test -race -count=1 ./...
+
+lint:
+	go vet ./...
+	gofmt -l .