fix #154 (task 1): Restrict AskOpenCanvas visibility to renderer boundaries

[ahmad2b]

This PR implements boundary validation for AskOpenCanvas visibility, ensuring it only appears for text selections within the code/markdown renderer.

Implementation

• Added isValidSelectionOrigin state for selection boundary tracking
• Created isWithinArtifact helper for DOM node validation
• Updated handleMouseUp to verify selection boundaries
• Added boundary condition checks to AskOpenCanvas rendering
• Implemented cleanup for selection state

Testing

• Verified AskOpenCanvas only shows within the renderer
• Confirmed no popups outside boundaries

Addresses first task from #154 - "Ensure the Ask Open Canvas input never shows up if the text is highlighted outside of the code/markdown renderer"

Let me know if you'd like any changes or any additional information.

Part of larger UX improvements outlined in #154.

askopencanvas.visibility.mp4

[vercel]

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[bracesproul]

great, thank you!