plan/11: Add GET /api/version endpoint

Adds handlers/version.go returning hardcoded {"version":"0.1.0","name":"director","commit":"unknown"},
wires GET /api/version into main.go next to /api/health, and adds
handlers/version_test.go using httptest (no DB dependency).

Co-Authored-By: director-agent <director-agent@dragonchain.com>

api/main.go

@@ -98,6 +98,9 @@ func main() {
 
 		// Stats
 		api.GET("/stats", h.GetStats)
+
+		// Version
+		api.GET("/version", h.GetVersion)
 	}
 
 	// WebSocket