feat(web): show a subtle turn completion tick

[saphid]

What Changed

Live turn completion can disappear into a quiet sidebar state. Show one small, silent check for 900 ms when a mounted foreground row observes the same turn go from running to successfully completed, then return to the existing presentation.

Why

The current and legacy sidebars share the tick. It requires a connected, synchronized shell with a stable connection generation. Old servers without the catch-up completion marker keep static statuses; hydration, reconnect, background, stop, interruption and error paths do not celebrate.

UI Changes

Cropped Electron component fixtures with synthetic state, using the actual proposed components. The before fixture reproduces the existing presentation; these clips do not establish backend or provider execution.

Before	After

Short playable video · Before recording

Validation: 141 focused sidebar/status tests, targeted lint/format and web typecheck passed. Electron component recording covers running → completed → settled, failure and reconnect catch-up using the actual reducer and glyph. Reduced motion shows a static tick; catch-up produced zero ticks. A live provider turn and the legacy sidebar were not exercised end to end.

Fresh GPT-5.6 Sol read-only source review found no actionable findings against the four frozen feature changes and coding standard 144fbf46af335d8d18a95c8d4b4f2e9e0207fa2e. The direct claude -p --model claude-opus-5 --effort high --tools Read,Grep,Glob --permission-mode plan review launch exited 1 before model execution because OAuth refresh failed. Cross-provider review therefore did not occur.

This draft targets whimsy/electron-base-20260905 at reviewed revision d7462d29, because the working revision diverges from fork main. Only this concern is in the diff. Web and Electron share the renderer; React Native mobile is unchanged and untested. No packaged Nightly build was installed.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for UI changes
• I included a video for animation/interaction changes

Built with GPT-6 Astra (integration and spectrum) and GPT-5.6 Sol (bounded feature workers and fresh source review), using the Codex harness in T3 Code.

[github-actions]

Thread transfer impact

⚠️ The latest CI run did not produce a thread transfer result for 0c6a040.

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