fix(deep-wiki): raise diagram zoom controls above SVG content

[arimu1]

Fixes #367

Summary

• Add position: relative and z-index: 10000 to .diagram-zoom-controls in the deep-wiki build template
• Keeps zoom/close buttons clickable when a panned or zoomed Mermaid SVG overlaps the control bar (the overlay already uses z-index: 9999, but the controls bar had no stacking context)

Test plan

• Generate a deep-wiki site with a Mermaid diagram (/deep-wiki:build)
• Click a diagram to open the zoom modal
• Pan the diagram upward and/or zoom in until the SVG overlaps the control bar
• Confirm +, −, Reset, and ✕ buttons remain clickable
• Confirm Esc and overlay click-to-close still work

Made with Cursor

[Copilot]

Pull request overview

Raises diagram zoom controls above overlapping Mermaid SVG content so controls remain clickable.

Changes:

• Adds a positioned stacking context to the controls.
• Sets controls above the zoom overlay content.