Summary

Keep cached session todos intact when the user manually stops an active turn.

Why

Fixes the manual Stop path from #319. The Todo dock already stays mounted while todo data exists, but the abort handler was clearing the local todo cache before the backend had cleared the todo list.

Related Issue

Fixes #319.

How To Verify

bun install --frozen-lockfile
bun --cwd packages/app test:unit src/components/prompt-input/submit.test.ts
bun --cwd packages/app typecheck
git diff --check
bun --cwd packages/app playwright test e2e/session/session-composer-dock.spec.ts --grep "todo dock"

Screenshots or Recordings

Not attached. The change preserves existing UI state and does not alter visible copy. The behavior is covered by a focused unit regression and the existing Todo dock E2E.

Checklist

• I linked the related issue, or stated why there is no issue
• This PR has type, scope, and priority labels, or I requested maintainer labeling
• I listed the relevant verification steps, including tests when behavior changed
• I manually checked visible UI or copy changes when needed, with screenshots or recordings
• I considered macOS and Windows impact for desktop, packaging, updater, signing, paths, shell, or permissions changes
• I called out docs, release notes, dependencies, permissions, credentials, deletion behavior, or generated/local file changes when relevant
• I am targeting dev, and my PR title and commit messages use Conventional Commits in English