bug: schedule editor hides args when input schema is unavailable

[feibin95]

Describe the bug

When editing a schedule whose target script/flow input schema is unavailable or has no properties, the schedule editor can hide existing schedule args and show the runnable as taking no arguments.

This is confusing when schedule.args is non-empty: the schedule will still pass args at runtime, but the UI does not expose them for review or editing.

The schema-driven form should remain the primary UI when an input schema is available. This issue is about the fallback behavior when the schema form cannot be rendered.

To reproduce

1. Create or open a schedule whose args contains at least one value.
2. Point it at a script or flow whose input schema is unavailable, empty, or has no properties.
3. Open the schedule editor and inspect the runnable arguments section.
4. The existing schedule args are not shown; the UI indicates that the script/flow takes no argument.

Expected behavior

If the schedule has existing args but the input schema cannot be used to render SchemaForm, the editor should still expose the stored args, for example as a raw JSON fallback.

If raw JSON is not the desired UX, it would still be useful for the UI to avoid implying that the schedule has no args when schedule.args is non-empty.

Screenshots

No screenshot available yet.

Browser information

Local dev browser.

Application version

Observed against current main around 92c21bbe65.

Additional Context

I have a small local candidate patch that keeps SchemaForm as the preferred path and only shows raw JSON when the runnable input schema is unavailable or non-renderable. I wanted to confirm the intended fallback behavior before opening a PR.