A builder's brief says to run `bun test $(bun scripts/fast.ts)` and the type check before pushing, not the whole suite #6571

Done:

• [ ] The builder brief in src/crew/brief.ts names bun install (when node_modules is missing), bun x tsc --noEmit and bun test $(bun scripts/fast.ts) as the steps before a push, and says the forge runs the full check.
• [ ] A brief test asserts the line is present for a builder and absent for a planner.

Files: src/crew/brief.ts, its test.