feat: wire up Version variable for GoReleaser ldflags

Replace hardcoded "0.5.0" with cmd.Version variable injected by
GoReleaser at build time. Falls back to "dev" for local builds.

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

Author: gcmsg

internal/cmd/mcp.go

@@ -69,7 +69,7 @@ func runMCPServe(args []string, serverURL string) int {
 	// Create MCP server.
 	server := mcp.NewServer(&mcp.Implementation{
 		Name:    "peerclaw",
-		Version: "0.5.0",
+		Version: Version,
 	}, nil)
 
 	// Register available tools.

internal/cmd/root.go

@@ -12,6 +12,9 @@ func addTokenFlag(fs *flag.FlagSet, token *string) {
 	fs.StringVar(token, "token", t, "JWT auth token (or PEERCLAW_TOKEN env)")
 }
 
+// Version is set by GoReleaser via ldflags at build time.
+var Version = "dev"
+
 const defaultServer = "http://localhost:8080"
 
 // Run executes the CLI with the given arguments.
@@ -61,7 +64,7 @@ func Run(args []string) int {
 		printUsage()
 		return 0
 	case "version":
-		fmt.Println("peerclaw version 0.5.0")
+		fmt.Printf("peerclaw version %s\n", Version)
 		return 0
 	default:
 		fmt.Fprintf(os.Stderr, "unknown command: %s\n\n", args[0])