feat(api): Enable anonymous read access and server-side pagination for core resources:

[Sainava]

📝 Description

Enable anonymous read access and server-side pagination for core resources:

Permissions: IsAuthenticatedOrReadOnly for Region, Category, Technique (writes still auth-only).
Visibility: TechniqueViewSet returns all for staff; only is_published=True for others.
Pagination: Global PageNumberPagination via DefaultPagination (page_size=12, page_size query param).
Docs: [API_Documentation.md] updated with “Pagination & Filtering,” query params, examples, and response shape.
Tests: Added APITestCase for anonymous/staff visibility and pagination (including page_size override).

🔗 Related Issue

Fixes #55

🔄 Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🎨 UI/UX improvement
• ⚡ Performance improvement

🧪 Testing

• I have performed a self-review of my code
• Code has been tested locally
• Tests pass (if applicable)
• No new warnings introduced

📱 Frontend Changes (if applicable)

• Responsive design tested
• Cross-browser compatibility checked
• Accessibility guidelines followed

🔧 Backend Changes (if applicable)

• Database migrations created (if needed)
• API endpoints tested
• Authentication/authorization verified

📋 Additional Notes

Optional follow-up: add default ordering in Category/Region Meta to silence pagination warnings.
Frontend should consume results and use next/previous for pagination; no breaking changes to write endpoints.

✅ Checklist

• My code follows the project's coding standards
• I have updated documentation where necessary
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works

This will be an official contribution for OSCI'25

[github-actions]

Thanks for creating a PR for your Issue! ☺️

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In the meantime, please double-check the file changes and ensure that all commits are accurate.

If there are any unresolved review comments, feel free to resolve them. 🙌🏼

[AvishkarPatil]

@Sainava Thanks for update