Move neutral join/leave handlers into GmRelay.Shared so Telegram and Discord share capacity, waitlist, duplicate-click, and schedule-update behavior.
Add Discord component routing for join_session and leave_session buttons with deferred ephemeral replies and serialized schedule message updates.
Bump version to 2.5.0 and update Discord docs.
Refs #29
Introduce platform-neutral PlatformKind, PlatformUser, PlatformGroup, and IPlatformMessenger contracts in GmRelay.Shared.
Route Telegram session schedule updates, direct notifications, interaction replies, and calendar export through TelegramPlatformMessenger while preserving existing Telegram behavior.
Bump version -> 2.0.1