lint: fix errcheck in api/api.go debug log writes

Add lint.Fprintf and lint.Write helpers for safe writer operations.
Use lint.Fprintf for unchecked fmt.Fprintf calls in webhookFieldseeker.

api/api.go

@@ -294,7 +294,7 @@ func webhookFieldseeker(w http.ResponseWriter, r *http.Request) {
 	}
 	for name, values := range r.Header {
 		for _, value := range values {
-			fmt.Fprintf(file, "%s: %s\n", name, value)
+			lint.Fprintf(file, "%s: %s\n", name, value)
 		}
 	}
 
@@ -323,11 +323,11 @@ func webhookFieldseeker(w http.ResponseWriter, r *http.Request) {
 		}
 
 		if len(body) == 0 {
-			fmt.Fprintf(file, "(empty body)")
+			lint.Fprintf(file, "(empty body)")
 		}
 	}
 
-	fmt.Fprintf(file, "\n=== End of request ===\n\n")
+	lint.Fprintf(file, "\n=== End of request ===\n\n")
 
 	// Extract the crc_token value for the signature portion
 

lint/error.go

@@ -2,6 +2,8 @@ package lint
 
 import (
 	"context"
+	"fmt"
+	"io"
 
 	"github.com/rs/zerolog/log"
 )
@@ -33,3 +35,19 @@ func LogOnErrRollback(f ErrorableCtx, ctx context.Context, msg string) {
 		log.Error().Err(e).Msg(msg)
 	}
 }
+
+// Fprintf writes a formatted string to w, logging any error.
+func Fprintf(w io.Writer, format string, args ...any) {
+	_, err := fmt.Fprintf(w, format, args...)
+	if err != nil {
+		log.Error().Err(err).Msg("fprintf failed")
+	}
+}
+
+// Write writes p to w, logging any error.
+func Write(w io.Writer, p []byte) {
+	_, err := w.Write(p)
+	if err != nil {
+		log.Error().Err(err).Msg("write failed")
+	}
+}