Workflow tool: scriptPath + name args, relaunch-based resume

[Michaelliv]

Extend workflow tool schema:

• script: inline (existing)
• scriptPath: absolute path (saved or workflow-runs)
• name: slug resolving via saved workflow loader

Behavior:

• scriptPath/name load the script from disk
• Optionally accept taskId to reuse a paused task (status -> running)
• Re-runs from the top; true step-skip lives in a separate issue

Parent: #1