docs: polish open source project docs

[faraa2m]

Summary

• Add contributor, security, code of conduct, and PR template docs
• Refresh README status for the published @RouterLab packages
• Make eval:smoke truly fixture-backed so it no longer reaches Hugging Face
• Add a patch Changeset for @routerlab/core and @routerlab/cli

Validation

• bun install --frozen-lockfile
• bun run --filter '*' build
• bun test
• bun run eval:smoke

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Keep smoke fixtures out of shared dataset cache

seedSmokeFixtures() writes fixture files to datasetCachePath(filename), which is the same cache location used by normal frontier/frontier-all dataset loaders. After someone runs bun eval/cli.ts smoke, later non-smoke evals will read these tiny fixture caches instead of fetching the real HF datasets, silently producing incorrect frontier/quality results until the cache is manually cleared.

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