Release 2.11.0 (#1164)

Minor release. Main theme is video degradation preference alignment with
the other SDKs, plus hardening around protobuf enums and the backup
codec lifecycle, new DisconnectReason members, and a dependency refresh.

## Changes

Added
- DisconnectReason members for newer server reasons (roomClosed,
migration, sipTrunkFailure, ...)
- DevelopmentTokenSource, replaces the deprecated SandboxTokenSource

Changed
- Default degradation preference follows track source (camera keeps
framerate, screen share keeps resolution), also applied to the backup
codec sender
- Unknown protobuf enum values from newer servers fall back to safe
defaults instead of erroring
- Protocol definitions v1.50.4
- Dependency updates (device_info_plus 13.x, connectivity_plus 7.3.1,
dart_webrtc 1.8.1, synchronized 3.4.1, uuid 4.6.0)
- Modernized example app (redesigned connect page, connection history,
room header, focus layout, in-room messages panel)

Fixed
- Room.connect no longer ignores the roomOptions argument passed to it
(note: apps passing e2eeOptions through this deprecated parameter were
silently running without e2ee, encryption now actually activates for
them)
- Backup codec state cleared on unpublish and full reconnect, backup
codecs republish correctly after reconnect
- Room.getSid() resolves when the room sid arrives after the join
response
- DegradationPreference.disabled maps to maintainFramerateAndResolution
as WebRTC defines it

Author: hiroshihorie