refactor(run): extract 4 helpers from 243-line cmdRunHeadless

[la14-1]

Why: cmdRunHeadless (243 lines) mixed input validation, platform-specific script fetching, and post-run record extraction into a single monolith. Extracting these into focused helpers makes each phase independently testable and reduces the orchestrator to ~30 lines.

Changes

Extracted 4 helpers from cmdRunHeadless in packages/cli/src/commands/run.ts:

1. validateHeadlessInputs — input validation, manifest loading, name resolution, entity + credential checks
2. fetchAndRunWindows — Windows bundle download (local or remote) + bun execution
3. fetchAndRunUnix — macOS/Linux script download (CDN → GitHub fallback) + shell execution
4. extractConnectionFields — post-run history lookup with per-field validation

cmdRunHeadless is now a thin orchestrator: validate → run (platform branch) → extract fields → output.

Also bumps CLI version 1.0.20 → 1.0.21.

Test plan

• bunx @biomejs/biome check src/ — 0 errors
• bun test — 2106 pass (2 pre-existing flaky failures unrelated to this change)
• Headless-specific tests pass: bun test src/__tests__/headless*.test.ts src/__tests__/cmd-run*.test.ts — 31 pass, 0 fail

-- refactor/complexity-hunter

[la14-1]

Rebased onto main to resolve merge conflicts (package.json version bump).

-- refactor/pr-maintainer

[la14-1]

Fixed CI: removed duplicate "version" key in packages/cli/package.json that was introduced during the rebase. bun install was failing with Duplicate key "version" in object literal. CI should pass now.

-- refactor/pr-maintainer

[la14-1]

This PR has been open for 3+ days with all CI checks passing (ShellCheck, Mock Tests, Biome Lint, Unit Tests, macOS Compatibility — all SUCCESS). It is mergeable with no conflicts.

Requesting human review when convenient.

-- refactor/pr-maintainer

[la14-1]

Rebased onto main (dropped the now-redundant duplicate-version-key fix commit). Branch is clean with 1 commit. Awaiting human review.

-- refactor/pr-maintainer

[la14-1]

This PR is ready for review. All CI checks pass and there are no merge conflicts.

-- refactor/pr-maintainer

[la14-1]

Rebased onto main (was 4 commits behind). Clean rebase, no conflicts.

-- refactor/pr-maintainer

[la14-1]

Verified in worktree: tests pass (2236/2238, same 2 pre-existing failures as main), lint clean (biome 0 errors). PR is mergeable and ready for review.

-- refactor/pr-maintainer