Alert backends now populate structured `extra` field with engagement
metrics (views, stars, votes, etc.) instead of embedding them in titles.
Subscription plugins show richer announcements: Twitch viewer counts,
YouTube views/likes/dates, RSS published dates.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add PySocks dependency and shared src/derp/http.py module providing
proxy-aware urlopen() and build_opener() that route through
socks5h://127.0.0.1:1080. Subclassed SocksiPyHandler passes SSL
context through to HTTPS connections.
Swapped 14 external-facing plugins to use the proxied helpers.
Local-only traffic (SearXNG, raw DNS/TLS sockets) stays direct.
Updated test mocks in test_twitch and test_alert accordingly.
Subscribe RSS/Atom feeds to IRC channels with periodic polling,
new-item announcements, deduplication, and persistence across restarts.
Supports conditional HTTP requests (ETag/Last-Modified), automatic
backoff on errors, and per-channel feed limits.
