cli: update banner art and simplify onboard help text

Switch to block-style ASCII art for the PAPERCLIP banner and use
unicode box-drawing separator. Shorten the onboard outro run hint.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cli/src/commands/onboard.ts

@@ -248,7 +248,7 @@ export async function onboard(opts: OnboardOptions): Promise<void> {
 
   p.note(
     [
-      `Run now: ${pc.cyan("paperclipai run")} (onboard + doctor + start in one command)`,
+      `Run: ${pc.cyan("paperclipai run")}`,
       `Reconfigure later: ${pc.cyan("paperclipai configure")}`,
       `Diagnose setup: ${pc.cyan("paperclipai doctor")}`,
     ].join("\n"),