chore: remove all skills

[sunwrobert]

Summary

Remove all contents of skills/ and the six .claude/skills/ symlinks. Update the README and agent guidance to remove obsolete skill references, and stop the project initializer from downloading deleted skills while retaining its settings setup.

Validation

• bun run check passed.
• bun run check-types passed.
• bash -n scripts/init-project.sh passed.
• Ran the initializer against a fresh temporary directory, including after pushing: settings downloaded successfully and no skills directory was created.
• git diff --check passed.
• bun run test:unit exits with “No test files found”; the repository contains no unit tests.