Add build target with version injection via ldflags

- Update Makefile to inject VERSION and GIT_COMMIT at build time
- Change Version from const to var to allow ldflags injection
- Add build target to create binary with proper version info

Makefile

@@ -1,4 +1,8 @@
-.PHONY: test lint check-fmt fmt
+VERSION := 1.0.0
+GIT_COMMIT := $(shell git rev-parse HEAD)
+LDFLAGS := -X 'git.eeqj.de/sneak/smartconfig.Version=$(VERSION)' -X 'git.eeqj.de/sneak/smartconfig.GitCommit=$(GIT_COMMIT)'
+
+.PHONY: test lint check-fmt fmt build
 
 test: lint check-fmt
 	go test -v ./...
@@ -14,4 +18,7 @@ check-fmt:
 	fi
 
 fmt:
-	go fmt ./...
+	go fmt ./...
+
+build:
+	go build -ldflags "$(LDFLAGS)" -o smartconfig ./cmd/smartconfig

version.go

@@ -1,7 +1,7 @@
 package smartconfig
 
-// Version is the current version of smartconfig
-const Version = "1.0.0"
+// Version is the current version of smartconfig (set at build time with -ldflags)
+var Version = "dev"
 
 // GitCommit is the git commit hash (set at build time with -ldflags)
 var GitCommit = "unknown"