Remove input type checking in favour of explicit `.DescribeProtocolAsync()` flow. Also removes `.AsAgentAsync()` as the validation happens at workflow run time. This makes it easier to use Workflows with DI without resorting to async-over-sync.
* refactor: remove unused internals
* feat: Execution Mode for sharing a workflow among concurrent runs
* feat: Update WorkflowHostAgent to support concurrent execution
* Also update AsAgent APIs to support injecting a CheckpointManager and an IWorkflowExecutionEnvironment
* fix: Make Read logic consistent in DeclarativeWorkflowContext
- Added ChatMessage[] handler to ConfigureRoutes to support array dispatch
- Workflow runtime can dispatch messages as either List<ChatMessage> or ChatMessage[]
- Added 10 comprehensive unit tests validating message routing behavior
- Tests ensure functionality and protect against future refactoring (issue #782)
- Updated code comments to reflect exact-type-matching requirement
Fixes issue where raw WorkflowBuilder with AIAgent nodes failed to receive
initial messages due to missing array type handler.