feat: add evals infra

[hyf0]

• See https://github.com/vuejs-ai/skills/blob/1fe81810af24cce9ce7f100e492d8e0f94932e67/evals/README.md to understand how it works
• Each skill * reference is a situation we need to test.
• Each situation will be tested with 3 model tiers, haiku, sonnet, opus. We could add codex's model later.
• Each situation will have 3 evaluations to check if it works.
• Each evaluation will be checked via two steps
  • One is the baseline that doesn't contain skills
  • One is the with-skill that contains the skills
    • Each step will run two times to ensure stablity

[Copilot]

Pull request overview

This PR adds an evaluation infrastructure to systematically test and validate Vue.js skills. The system runs automated tests comparing model performance with and without skills installed.

Changes:

• Added 27 evaluation scenarios across 9 skill categories
• Each scenario includes a self-contained Vue project with test assertions
• Implemented CLI runner with support for multiple models and tiers

Reviewed changes

Copilot reviewed 266 out of 356 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
evals/package.json	Package configuration for evals workspace
evals/lib/types.ts	TypeScript type definitions for eval system
evals/lib/runner.ts	Core eval execution engine with Claude Code integration
evals/lib/skill-coverage.test.ts	Automated test ensuring all skills have evals
evals/suites/skills/*/eval.json	Eval configurations with queries and expected behaviors
evals/suites/skills/*/eval.ts	Vitest test files validating generated code patterns
evals/suites/skills/*/results.json	Recorded results with timestamps from future dates
evals/README.md	Documentation for eval system usage
AGENTS.md	Development workflow and evaluation guidelines
README.md	Updated validation process documentation

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[serkodev]

@codex review this PR

[chatgpt-codex-connector]

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[serkodev]

LGTM, optional to follow the review by CodeX