docs: add first-principles guidance

[overtrue]

Pull Request

Description

Add first-principles guidance for agents: clarify the underlying goal, discuss unclear intent, and recommend a shorter path when one exists.

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 change)
• Documentation update
• Code refactoring
• Performance improvement
• Test improvements
• Security fix

Testing

• Unit tests added/updated
• Manual testing completed

pnpm type-check
pnpm lint
pnpm exec prettier --check AGENTS.md
pnpm test:run

Checklist

• Code follows the project style guidelines
• Self-review completed
• TypeScript types are properly defined
• All commit messages are in English (Conventional Commits)
• All existing tests pass
• No new dependencies added, or they are justified

Related Issues

N/A

Screenshots (if applicable)

N/A

Additional Notes

The full formatting check still reports pre-existing formatting drift in components/object/tiff-viewer.tsx; the changed file passes Prettier.