fix(beads): handle deprecated Type field in listViaRPC

The RPC path for List operations was not converting opts.Type to a label,
causing all issues to be returned when the daemon was running. This resulted
in gt mq list showing all beads (including wisps) instead of just merge-requests.

The subprocess fallback path had this conversion, but RPC did not.

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

internal/beads/beads_rpc.go

@@ -242,8 +242,12 @@ func (b *Beads) listViaRPC(opts ListOptions) ([]*Issue, error) {
 	}
 
 	// Convert Label to Labels array if set
+	// Also handle deprecated Type field by converting to gt: label
 	if opts.Label != "" {
 		args.Labels = []string{opts.Label}
+	} else if opts.Type != "" {
+		// Deprecated: convert type to label for backward compatibility
+		args.Labels = []string{"gt:" + opts.Type}
 	}
 
 	// Handle priority: -1 means no filter