feat: make SendTimeout effect

[ArgoZhang]

Link issues

fixes #31

Summary By Copilot

Regression?

• Yes
• No

Risk

• High
• Medium
• Low

Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• Merge the latest code from the main branch

[Copilot]

Pull Request Overview

This PR implements a SendTimeout feature for the TCP socket client, allowing users to configure a timeout for send operations. The implementation adds timeout logic to the SendAsync method and updates corresponding test cases.

Key changes:

• Adds timeout functionality to the SendAsync method using CancellationTokenSource
• Updates test cases to use the new timeout feature and modernized async receive methods
• Replaces buffer-based receive operations with direct memory-based operations in tests

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/Longbow.TcpSocket/Interface/DefaultTcpSocketClient.cs	Implements SendTimeout logic in SendAsync method using linked cancellation tokens
test/UnitTestTcpSocket/TcpSocketFactoryTest.cs	Updates tests to set SendTimeout and modernizes receive operations to use memory-based APIs

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