feat(web): optional toggle to show rate limits in sidebar

[imabdulazeez]

What Changed

Adds an optional usage-limit indicator above the sidebar footer controls.

For the provider selected in the current chat, the compact indicator shows the remaining quota in its shortest reported window, such as Claude's five-hour limit. Hovering or focusing it expands an in-sidebar panel showing every reported limit window and reset countdown for that provider.

The indicator is disabled by default. It can be enabled with the Show in sidebar toggle at the top of the Usage → Limits view.

This is a web/desktop UI addition built on the provider usage-limit data introduced in #9507. It does not add another provider probe, polling loop, or usage-limit backend.

Why

The Limits view provides the complete account overview, but checking it requires leaving the active chat. The shortest-duration window is usually the limit most likely to interrupt the current task, so showing that value in the sidebar makes it available at a glance.

Keeping the feature opt-in avoids adding permanent sidebar noise for users who do not need it. Expanding on hover or keyboard focus provides the remaining windows without duplicating the full Limits page.

This follows up on earlier sidebar proposals such as #4611, #6264, and #8138 while reusing the usage-limit architecture already merged through #9507.

UI Changes

Before: provider limits are available only from Usage → Limits.

After: when Show in sidebar is enabled, the active provider's shortest usage window appears above the sidebar footer controls. Hovering or focusing it shows all reported windows inside the sidebar boundary.

Checklist

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

Note

Add optional sidebar rate-limit indicator with sidebarUsageLimitsEnabled toggle

• Adds a new sidebarUsageLimitsEnabled client setting (default false) so users can opt into showing usage limits in the sidebar footer
• Renders a compact shortest-window remaining-percentage indicator and an expanded view with all sorted usage windows via the new SidebarUsageLimits component in SidebarChrome.tsx
• Resolves provider limits by preferring provider-level limits, falling back to a matching usage-source account selected by driver and normalized email
• Adds a "Show in sidebar" toggle in the Limits view and documents the feature in usage.md

^{Macroscope summarized f18044d.}

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR adds a new opt-in sidebar quota experience, including provider matching, limit-window rendering, persistence, and interactive details through a substantial new component. Existing behavior remains unchanged by default, but the new product default and lack of feature-specific tests warrant human review.

Notes:

• Macroscope's correctness review did not run, so approvability was decided on eligibility alone.

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