docs: migrate docs foundations (overview, icons, radius, shadows, stroke and typography) to Mintlify

[Morosan]

Description

Adds the missing Foundations documentation pages.

Documentation

This PR adds and updates documentation in apps/beeq-docs:

• adds the Foundations overview page
• adds or updates the Foundations pages for icons, radius, shadows, stroke, and typography
• updates docs.json navigation to include the Foundations overview entry
• updates the typography token tables to include inline examples and match the migrated source content more closely

Checklist

• I have read the CONTRIBUTING document.
• I have read the CODE OF CONDUCT document.
• I have reviewed my code.
• I have tested the changes locally.
• I have updated the documentation (if applicable).
• I have added unit tests and e2e tests (if applicable).
• I have requested reviews from relevant team members.

Additional Notes

• ❌ SVG assets (overview, anatomy, design guideline images) are still pending for all pages in this batch — placeholder <Frame> image paths are in place and will be replaced once assets are delivered.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud