feat(crewai-tools): add highlights to ExaSearchTool, rename from EXASearchTool

* feat(crewai-tools): add highlights to ExaSearchTool, rename from EXASearchTool

- Add a highlights init param so agents can get token-efficient excerpts instead of full pages
- Rename EXASearchTool to ExaSearchTool; keep EXASearchTool as a deprecated alias so existing imports keep working
- Update the docs and example to use highlights as the recommended option
- Add a small note that says Exa is the fastest and most accurate web search API
- Add tests for the new highlights param and the deprecation alias

* fix(crewai-tools): import order and module-level Exa for tests

- Reorder std-lib imports so ruff is happy with force-sort-within-sections.
- Import Exa at module level (with a fallback) so the existing test mocks resolve.
  The lazy install prompt still works if exa_py is missing.
- Allow content and summary to be a dict, matching highlights.
- Trim test file to the cases this PR introduces (highlights param and the
  EXASearchTool deprecation alias). Existing init-shape tests stay.

Co-Authored-By: ishan <ishan@exa.ai>

* chore(crewai-tools): drop self-explanatory comment on schema alias

Co-Authored-By: ishan <ishan@exa.ai>

* docs(crewai-tools): default highlights to True, drop summary from examples

Co-Authored-By: ishan <ishan@exa.ai>

* docs(crewai-tools): simplify highlights examples to highlights=True

Co-Authored-By: ishan <ishan@exa.ai>

* feat(crewai-tools): add x-exa-integration header for usage tracking

Co-Authored-By: ishan <ishan@exa.ai>

* docs(crewai-tools): add Exa MCP section and resources links

Co-Authored-By: ishan <ishan@exa.ai>

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Co-authored-by: ishan <ishan@exa.ai>
Co-authored-by: Greyson LaLonde <greyson.r.lalonde@gmail.com>
Co-authored-by: Lorenze Jay <63378463+lorenzejay@users.noreply.github.com>