fix(web): keep the ultrathink spectrum still at rest

[saphid]

What Changed

Ultrathink continuously rotated the composer border and icon colors, even while idle. Keep the spectrum as a static treatment and replace it with a system-color outline in forced-colors mode.

Why

The mode stays recognizable while the renderer can rest. Enabling and disabling ultrathink still uses the existing composer state.

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

Actual integrated Electron surface:

Validation: 13 focused composer-provider-state tests and web typecheck passed. In the real Electron composer the border reports animation-name: none. Before/after fixture recordings demonstrate activation, deactivation and idle behavior; reduced-motion and forced-color checks passed.

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]

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