fix(lucipres): increase render channel capacity to prevent dropped results

renderdonech was chan[4] — when more than 4 async markdown renders
were in-flight (rapid tab switching), render completions were silently
dropped via non-blocking alt send. The artifact stayed stuck with
rendering=1 and nil image, showing nothing when the tab was selected.

Increase to chan[32] so results are not lost during fast tab switching.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pdfinn

appl/cmd/lucipres.b

@@ -172,7 +172,7 @@ init(ctxt: ref Draw->Context, args: list of string)
 	# deliverevent() as soon as lucipres_g is set (before init completes).
 	# alt send on a nil channel is a fatal "dereference of nil" in Dis.
 	preseventch = chan[8] of string;
-	renderdonech = chan[4] of ref RenderResult;
+	renderdonech = chan[32] of ref RenderResult;
 
 	wmclient = load Wmclient Wmclient->PATH;
 	if(wmclient == nil) {