lint: fix errcheck for fmt.Fprintf/Fprint across multiple files

Add lint.Fprint helper for unchecked fmt.Fprint calls.
Use lint.Fprintf/Fprint in api/event.go, api/image.go, rmo/root.go.
Add explicit error check for fmt.Fprintf in middleware/terminal.go cW.

lint/error.go

@@ -51,3 +51,11 @@ func Write(w io.Writer, p []byte) {
 		log.Error().Err(err).Msg("write failed")
 	}
 }
+
+// Fprint writes a string to w, logging any error.
+func Fprint(w io.Writer, a ...any) {
+	_, err := fmt.Fprint(w, a...)
+	if err != nil {
+		log.Error().Err(err).Msg("fprint failed")
+	}
+}