fix: Capture stderr instead of suppressing in command execution

Several files were setting cmd.Stderr = nil, which hides potentially
critical error messages:

- prime.go: bd prime, gt mail check, and bd show commands now log
  stderr on failure for debugging
- orphans.go: git fsck now includes stderr in error messages
- patrol_helpers.go: bd list/show/catalog commands now log stderr

Daemon launch cases (up.go, daemon.go, daemon_check.go) correctly
use nil for I/O detachment but now have clarifying comments.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/orphans.go

@@ -124,14 +124,19 @@ func findOrphanCommits(repoPath string) ([]OrphanCommit, error) {
 	fsckCmd := exec.Command("git", "fsck", "--unreachable", "--no-reflogs")
 	fsckCmd.Dir = repoPath
 
-	var fsckOut bytes.Buffer
+	var fsckOut, fsckErr bytes.Buffer
 	fsckCmd.Stdout = &fsckOut
-	fsckCmd.Stderr = nil // Ignore warnings
+	fsckCmd.Stderr = &fsckErr
 
 	if err := fsckCmd.Run(); err != nil {
 		// git fsck returns non-zero if there are issues, but we still get output
 		// Only fail if we got no output at all
 		if fsckOut.Len() == 0 {
+			// Include stderr in error message for debugging
+			errMsg := strings.TrimSpace(fsckErr.String())
+			if errMsg != "" {
+				return nil, fmt.Errorf("git fsck failed: %w (%s)", err, errMsg)
+			}
 			return nil, fmt.Errorf("git fsck failed: %w", err)
 		}
 	}