[Fix] Sandbox yarn PATH and --no-verify git push delivery

[pridemusvaire]

Summary

• Enable Corepack yarn and reshim mise during worker setup so yarn is on PATH for husky pre-push hooks in sandboxes.
• Update Roomote delivery skills (push, create-pr, create-draft-pr, fix-pr, merge-conflict resolver, environment-setup) to push with --no-verify, since CI owns full-suite pre-push checks and sandbox hook failures were being misreported as missing GitLab credentials.

Root cause

GitLab OAuth/source-control proxy credentials were fine. Pushes failed because fleet-portal's .husky/pre-push requires yarn, which was not on the sandbox PATH (yarn: not found), and agents narrated that as a credential outage.

Test plan

• pnpm --filter @roomote/worker exec vitest run src/commands/setup/__tests__/mise.test.ts
• New sandbox task on fleet-portal: commit + push should succeed (with --no-verify) and open MR via manage_source_control
• Confirm worker logs show corepack yarn enable when yarn was missing

[roomote-roomote]

1 issue outstanding. See task

• knip.ts:73 Remove corepack from ignoreBinaries: pnpm knip reports Configuration hints (1): corepack apps/worker knip.ts Remove from ignoreBinaries, so the added entry leaves the required Knip check noisy on every run.

_{Reviewed 85953fa}

[pridemusvaire]

Closing: not merging upstream. The sandbox yarn PATH + git push --no-verify delivery fix was hot-deployed on our self-hosted VPS via a patched worker release; we can reopen if we want this in develop.