.NET: Fix source generator bug that silently drops base class handler registrations for protocol-only partial executors

[peibekwe]

Motivation and Context

ClassProtocolInfo didn't carry BaseHasConfigureProtocol, so CombineOutputOnlyResults couldn't know whether the base class already overrides ConfigureProtocol and this led to silent drop of base class handler registrations for protocol-only partial executors. This broke the CustomAgentExecutors sample.

Fixes #4202

Description

• Added BaseHasConfigureProtocol to ClassProtocolInfo
• Populated it via BaseHasConfigureProtocol in AnalyzeClassProtocolAttribute
• Used BaseHasConfigureProtocol in CombineOutputOnlyResults instead of hardcoded false value.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[Copilot]

Pull request overview

Fixes a .NET workflows source-generator bug where protocol-only partial executors could silently lose inherited ConfigureProtocol handler registrations (breaking the CustomAgentExecutors sample), by correctly carrying and propagating base-class protocol override information through generator analysis.

Changes:

• Extended ClassProtocolInfo to include BaseHasConfigureProtocol.
• Populated and propagated BaseHasConfigureProtocol through semantic analysis and protocol-only result combination.
• Updated the CustomAgentExecutors sample to be generator-compatible (partial + IO attributes) and added basic runtime error printing.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
dotnet/src/Microsoft.Agents.AI.Workflows.Generators/Models/ClassProtocolInfo.cs	Adds BaseHasConfigureProtocol to the protocol-only analysis model so the generator can preserve base protocol configuration.
dotnet/src/Microsoft.Agents.AI.Workflows.Generators/Analysis/SemanticAnalyzer.cs	Computes BaseHasConfigureProtocol during attribute analysis and uses it when combining protocol-only results (fixing the inheritance regression).
dotnet/samples/03-workflows/Agents/CustomAgentExecutors/Program.cs	Adjusts the sample executor to use generator-driven protocol declarations and prints workflow errors to aid diagnosis.