[Core] Add group member mute support

[sweetymajo]

This PR adds support for muting individual group members by exposing the MuteGroupMember API through MessageExt and implementing the corresponding operation event, service, and request packet using OidbSvcTrpcTcp.0x1253_1.
The implementation has been successfully built for all target frameworks supported.

[Copilot]

Pull request overview

This PR adds support for muting individual group members by introducing a new OIDB service (OidbSvcTrpcTcp.0x1253_1), its request/response packet models, and wiring it into the internal operation logic with a public MessageExt API entry point.

Changes:

• Added GroupMuteMemberService to send OIDB 0x1253 service 1 requests for member mute operations.
• Added protobuf packet models (D1253ReqBody / D1253RspBody) and protocol event request/response types for the operation.
• Exposed MuteGroupMember through OperationLogic and MessageExt, including UID resolution via the member cache.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Lagrange.Core/Internal/Services/System/GroupMuteMemberService.cs	Implements the new OIDB service handler for group member mute requests.
Lagrange.Core/Internal/Packets/Service/Oidb_0x1253.cs	Adds protobuf request/response models for OIDB 0x1253_1.
Lagrange.Core/Internal/Logic/OperationLogic.cs	Adds MuteGroupMember operation, resolving targetUin -> uid via cache/member list refresh.
Lagrange.Core/Internal/Events/System/GroupMuteMemberEvent.cs	Defines protocol event request/response types for the new operation.
Lagrange.Core/Common/Interface/MessageExt.cs	Exposes MuteGroupMember as a BotContext extension API.

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