End of April Improvements

A round of correctness and reliability improvements across messaging, rituals, worksheets and onboarding:

• Pinned message banner: concurrent pin requests are serialized, so a channel shows at most one pinned message, and anonymized messages stay out of the banner.
• New-message sound for thread replies: replies inside a message thread play the channel notification sound, matching top-level messages.
• Ritual documents: ritual documents in PROCESSING can self-recover, and a retry uses the generation job for the session type.
• Print dialog feedback: when the browser blocks the print popup (popup blockers, mobile Safari and similar), you see a clear toast message.
• Client onboarding redirect: when the original destination space or app has been removed, the redirect after completing the onboarding checklist falls back gracefully.
• Version update banner: the “new version available” refresh button keeps working even when an outdated bundle is loaded.