refactor(agent): finish renaming the primary director from skywalker to dispatch

[TheGreatAxios]

Summary

• Remove the SKYWALKER_TOOLS alias (hard cutover) and use DISPATCH_TOOLS in tests and comments.
• Replace Skywalker with dispatch in PRODUCT, ARCHITECTURE, and IMPLEMENTATION, including createDispatchSystemPrompt, the spawn_agent(agent=dispatch) refusal, and the --director default wording.
• Fix stale builder, counsel, critic, greybeard, and intern wording and the director count (20 to 10) in IMPLEMENTATION and ARCHITECTURE.

Verification

• bun run check passes (7,870 tests).
• rg -i skywalker finds nothing in docs, src, e2e, or scripts except a stale key in scripts/ci-timings.json.

Fixes CL-9656

[linear-code]

CL-9656