Bump version to 0.1.9 and add AI agent guidance

[Woojin-Crive]

Summary

• Bump package version from 0.1.8 to 0.1.9 in project metadata, setup metadata, and package version.
• Add canonical AGENTS.md guidance plus Claude, Gemini, Cursor, Codex, and GitHub Copilot entrypoints.
• Document the AI-agent guidance layout in the contributing docs and link it from README/MkDocs navigation.

Validation

• python3 setup.py --version -> 0.1.9
• python3 -m pytest tests/test_cache.py -> 2 passed
• python3 -m mkdocs build -> passed with existing docs warnings for older unnaved/link-check pages

[gemini-code-assist]

Code Review

This pull request updates the package version of zenoh-ros2-sdk from 0.1.8 to 0.1.9 in pyproject.toml, setup.py, and zenoh_ros2_sdk/__init__.py. There are no review comments, so I have no feedback to provide.

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