doctor: collapse healthy output to one line, add --verbose

A healthy host triggered ~20 PASS rows with details — too noisy for
the common case. Default now prints only fail/warn rows plus a
summary footer; an all-pass run collapses to a single line. Pass
--verbose / -v for the full per-check output.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/cli/printers.go

@@ -272,9 +272,34 @@ func printKernelCatalogTable(out anyWriter, entries []api.KernelCatalogEntry) er
 
 // -- doctor printer -------------------------------------------------
 
-func printDoctorReport(out anyWriter, report system.Report) error {
+func printDoctorReport(out anyWriter, report system.Report, verbose bool) error {
 	colorWriter, _ := out.(io.Writer)
+
+	var passes, warns, fails int
+	for _, c := range report.Checks {
+		switch c.Status {
+		case system.CheckStatusPass:
+			passes++
+		case system.CheckStatusWarn:
+			warns++
+		case system.CheckStatusFail:
+			fails++
+		}
+	}
+
+	if !verbose && warns == 0 && fails == 0 {
+		msg := fmt.Sprintf("all %d checks passed", passes)
+		if colorWriter != nil {
+			msg = style.Pass(colorWriter, msg)
+		}
+		_, err := fmt.Fprintln(out, msg)
+		return err
+	}
+
 	for _, check := range report.Checks {
+		if !verbose && check.Status == system.CheckStatusPass {
+			continue
+		}
 		status := strings.ToUpper(string(check.Status))
 		if colorWriter != nil {
 			switch check.Status {
@@ -295,5 +320,19 @@ func printDoctorReport(out anyWriter, report system.Report) error {
 			}
 		}
 	}
+
+	if !verbose {
+		if _, err := fmt.Fprintf(out, "\n%d passed, %s, %s\n", passes, pluralCount(warns, "warning"), pluralCount(fails, "failure")); err != nil {
+			return err
+		}
+	}
+
 	return nil
 }
+
+func pluralCount(n int, word string) string {
+	if n == 1 {
+		return fmt.Sprintf("%d %s", n, word)
+	}
+	return fmt.Sprintf("%d %ss", n, word)
+}