Docs: Reorganize various doc sections

[endigo9740]

Describe the Issue (screenshots encouraged!)

As we implemented our technical updates to the doc site, I think it will make sense to reorganize a number of sections of the documentation. Below are a few recommendations, but may be expanded over time.

• [x] Move the “Headless Integration” guides under the standard “Integrations” section. (Per #3991)
• [x] Move the Iconography section under the “Design System” category. (Per #3991)
• [x] Rename “Functional Components” → “Framework Components” (Per #3991)
• [ ] Consider sunsetting the Cookbook section and redistribute content (proposal)
• [x] Move the Tutorials > Figma guide under the Figma top-level section
• [x] Find a new home for the “Showcase” section

[endigo9740]

Proposed redistribution of Cookbook sections:

Free Blocks
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Alerts
Breadcrumbs
Chat
Dialog Element
Image Layouts
Logo Cloud
Scroll Containers
SVG Filters
Table of Contents

Guides
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Dynamic Theme Switching -> extend Theme docs
Light Switch -> extend Dark Mode docs

Replace w/ Zag Components
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Clipboard API -> Clipboard
Stepper -> Step

Remove / Out of Scope
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Floating UI Attachments

[endigo9740]

@Hugos68 let's handle the Cookbook stuff as part of the v5 update. I'll bump this ticket over to that Milestone.