docs, tool fixes, setup command, release notes

[willccbb]

Description

Prep for v0.1.9 release, including:

• doc updates, readme overhaul
• version bump
• fix for adding + removing tools
• allowing system_prompt field to be used with datasets with a 'prompt' column

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
• Test improvement

Testing

• All existing tests pass when running uv run pytest locally.
• New tests have been added to cover the changes

Checklist

• My code follows the style guidelines of this project as outlined in AGENTS.md
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Additional Notes

---

Note

Prepares v0.1.9 with env fixes, doc refresh, and supporting tooling.

• Versioning/Release: Bump to 0.1.9; add assets/release/RELEASE_v0.1.9.md.
• Env behavior: Environment now prepends system_prompt to existing prompts that lack a system message.
• Tool environments: ToolEnv/StatefulToolEnv now maintain per-tool monitor metrics when tools are added/removed via new ToolMonitorRubric.add_tool_metric/remove_tool_metric; avoids duplicates and keeps counts accurate.
• Tests: Add tests for tool add/remove behavior and rubric metric updates; extend error-path coverage.
• Docs: Overhaul README.md and docs/ (navigation updates, wording fixes); add synced AGENTS.md and environments/AGENTS.md.
• Dev tooling: New scripts/sync_agents_md.py and pre-commit hook to auto-sync docs; minor .gitignore updates.

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