fix(workflows): make managed YAML Prettier-stable

[artiphishle]

Summary

• format rendered workflow YAML with the published Devtools Prettier policy before managed-file synchronization
• retain token substitution and workflow semantics while preserving one trailing newline
• prove CI and release workflow sync is Prettier-stable and byte-idempotent

Validation

• bun test src/tools/workflows/index.test.ts src/tools/workflows/renderWorkflowAsync.test.ts
• bun run build
• bun run check-types
• bun run lint (42 pre-existing warnings, no errors)
• bun run knip:check
• bun run changeset:status
• bun run format and bun run format:check

bun run test has six unrelated APM packed-fixture failures caused by path-containment rejection for files beneath temporary unpacked fixture directories.

Changeset: patch for generated managed workflow output.

Closes #593

[artiphishle]

Review on 92cb5c0: implementation is correct. Shared Prettier formatting is applied at the renderer boundary, the sync/format/second-sync test proves byte stability, and PR CI ran the full bun run test step successfully.

The six locally reported APM temp-realpath failures are therefore not a regression introduced by this PR; GitHub's full test step is green on the same head.

Remaining work is repository coordination only: this branch is now behind current Devtools main, so rebase it, resolve any generated-workflow overlap against current main, rerun CI, then mark ready for review. No additional functional change is required by this review.

[artiphishle]

Review status: implementation direction is clean. Formatting through the published Devtools Prettier config is the right generic fix, and the sync -> Prettier-stable -> second-sync-unchanged regression covers the actual steady-state contract.

Keep this PR Draft for now. Its previously reported six full-suite failures are exactly the APM temporary-root issue now fixed by PR #604. After #604 lands, rebase/update this branch and rerun the full bun run test; only then should #594 be marked review-ready. No additional workflow-specific workaround is needed.