v1.3.3-beta.3 ShadowOB fork

ShadowOB fork release for Shadow connector integration.\n\nChanges:\n- Align DM channel listing with /api/channels/dm.\n- Send DM messages through /api/channels/{id}/messages.\n- Resolve DM attachments through /api/attachments/{id}/media-url.\n- Build with no_web tag for embedded connector usage.