#149 pstack: give poteto-mode a human display name

Summary

• Sets name: Poteto Mode in poteto-mode's frontmatter. The name field is the display label in the slash menu; skill identity and /poteto-mode resolution derive from the folder path, so routing is unchanged. Unquoted bare string, same pattern as similar display names elsewhere.

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[!NOTE]
Low Risk
Single frontmatter label change with no runtime, routing, or data logic.

Overview
Updates the name field in poteto-mode skill frontmatter from poteto-mode to Poteto Mode so the slash menu shows a readable label.

Skill routing still uses the folder path and /poteto-mode; only the UI display string changes.

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