Add compact Ponytail builder guidance

[TheGreatAxios]

Summary

• Bakes compact Ponytail guidance into Builder by default while keeping Skywalker free of Ponytail internals.
• Replaces Builder's broad native-integration default with a compact native-runtime skill and stops baking TypeScript guidance into every Builder prompt.
• Updates skill catalog and director tests to pin compact default context and optional review/audit guidance.

Verification

• bun test src/agent/directors/bake-skills.test.ts src/agent/directors/builder/package.test.ts src/agent/directors/identity.test.ts src/agent/directors/skywalker/package.test.ts tests/unit/corbits-skills-catalog.test.ts passes
• bun run typecheck passes
• bun run check passes

Fixes CL-7470

[linear-code]

CL-7470