Allow setting Memo when starting a workflow from the UI

Is your feature request related to a problem? Please describe.

When starting a workflow from the Temporal UI, there is currently no option to set memo.

Memo is commonly used to attach contextual metadata to workflow executions. When workflows are started manually from the UI (e.g. for debugging or operational purposes), there is no way to provide this metadata, which makes these executions behave differently from those started via SDK.

Describe the solution you'd like

Add an optional Memo section in the "Start a Workflow" form.

For example:

• A JSON editor field (similar to Input Data)
• Simple key-value inputs
• Ideally supporting the same encoding options (json/plain, json/protobuf)

This would allow setting memo at workflow start, just like via SDK.

Describe alternatives you've considered

The current workaround is to:

• Start workflows programmatically via SDK, or
• Adjust workflow logic to tolerate missing memo

Neither is ideal when starting workflows directly from the UI for testing or operational tasks.

Additional context

Memo is already visible in the Workflow Details view, but it cannot be set when starting a workflow from the UI.

Start by locating the "Start a Workflow" form and its existing Input Data editor, then trace how the form submits a workflow start request. Compare that path with the Memo shown in the Workflow Details view and confirm the supported encoding options. Done means an optional Memo section can provide metadata when starting a workflow without affecting starts that omit it.