Add `proxy` config option to server (IRC), teams, telegram, and mumble
sections. IRC defaults to false (preserving current direct-connect
behavior); all others default to true. The `derp.http` module now
accepts `proxy=True/False` on urlopen, create_connection,
open_connection, and build_opener -- when false, uses stdlib directly.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
TCP/TLS connection over SOCKS5 proxy to Mumble servers for text chat.
Minimal varint/field protobuf encoder/decoder (no external dep) handles
Version, Authenticate, Ping, ServerSync, ChannelState, UserState, and
TextMessage message types. MumbleBot exposes the same duck-typed plugin
API as Bot/TeamsBot/TelegramBot. 93 new tests (1470 total).
