roadmap: Remove PerplexitySearchTool from deprecations

[marklysze]

Why are these changes needed?

Based on community feedback and use of functionality planned for deprecation, this PR will remove items from deprecation.

This will remain open until 0.13.

Restoring:
2026-04-26: PerplexitySearchTool

Related issue number

N/A

Checks

• I've included any doc changes needed for https://docs.ag2.ai/. See https://docs.ag2.ai/latest/docs/contributor-guide/documentation/ to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
...tools/experimental/perplexity/perplexity_search.py	87.80% <ø> (-0.30%)	⬇️

... and 54 files with indirect coverage changes

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