Implemented confi snapshots

internal/datasource/synthetic/definition.go

@@ -21,6 +21,12 @@ type SignalDef struct {
 	Visibility string `json:"visibility,omitempty"`
 	Owner      string `json:"owner,omitempty"` // creator identity (stamped server-side)
 	Panel      string `json:"panel,omitempty"` // bound interface id for "panel" visibility
+
+	// Version and Tag implement git-style revisioning. Version is bumped on
+	// every UpdateSignal; superseded revisions are kept as backup files. Tag is
+	// an optional human label for a revision (e.g. "restored from v3").
+	Version int    `json:"version,omitempty"`
+	Tag     string `json:"tag,omitempty"`
 }
 
 // InputRef names one upstream signal used as input to the pipeline.