refactor: remove dead task helper and normalize internal test hooks

[steipete]

What Problem This Solves

The final source sweep found an unused task-graph command collector and internal test hooks whose names required lint suppression.

User Impact

No CLI behavior or public configuration changes.

Why This Change Was Made

Delete the unreferenced collector and give the internal hooks the same descriptive naming used by the provider modules. Remove the now-unneeded suppression comments rather than changing lint rules.

Evidence

• pnpm typecheck, pnpm lint, pnpm format:check, focused mapper/provider/retry tests (189 passed), and pnpm build passed.
• Isolated Codex autoreview: scoped-clean at P0–P2 against the final formatted files.
• Live rebuilt CLI walkthrough with the deterministic mock provider: mapped 4 features, reviewed 3, reported 2 findings, inspected and previewed a fix, revalidated, and cleaned stale locks.
• Repository-wide symbol search confirmed the removed helper had no callers.

[clawsweeper]

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ClawSweeper picked this up.

Pull request received. I will update this pull request when review starts.

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[clawsweeper]

ClawSweeper status: review started.

I am starting a fresh review of this pull request: refactor: remove dead task helper and normalize internal test hooks This is item 1/1 in the current shard. Shard 0/1.

This placeholder means the worker is alive and reading the current context. I will edit this same comment with the actual review when the claws are done clicking.

Crustacean status: shell secured, claws on keyboard, evidence pebbles being sorted.