When secrets/flaskpaste/derp.crt and derp.key are present, load them
into the SSL context for mutual TLS auth and skip the PoW challenge
entirely. Fall back to PoW only when no client cert is available.
- PoW-authenticated paste creation and URL shortening via FlaskPaste
- !paste <text> creates a paste, !shorten <url> shortens a URL
- Module-level shorten_url/create_paste helpers for cross-plugin use
- Alert plugin auto-shortens URLs in announcements and history output
- Custom TLS CA cert support via secrets/flaskpaste/derp.crt
- No SOCKS proxy -- direct urllib.request to FlaskPaste instance