refactor(skills): stop injecting Einai by default

[birdmanmandbir]

Summary

• make FlickNote the only default injected role skill
• remove the implicit dependency on the external Einai skill source
• update role skill tests for the reduced default set

The ei ask CLI remains available when explicitly used; it is no longer injected into every role prompt.

Verification

• go test ./internal/config ./cmd ./internal/scaffold
• golangci-lint run --new-from-rev=origin/main
• git diff --check