Sidebar toggle not visible at iPad Pro viewport dimensions

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## Summary

When the left sidebar is hidden at iPad Pro viewport dimensions (~1024x1366), the sidebar toggle button disappears and there's no way to bring the sidebar back without resizing to a different viewport width.

## Steps to reproduce

1. Open any docs page (e.g., `/influxdb3/core/api/cache-distinct-values/`)
2. Resize the browser to iPad Pro dimensions (~1024px wide)
3. Hide the left sidebar using the sidebar toggle
4. The sidebar toggle button disappears — no way to re-show the sidebar

## Expected behavior

The sidebar toggle button should remain visible at all viewport widths where the sidebar can be hidden, allowing users to toggle it back on.

## Actual behavior

The toggle button is not rendered/visible at iPad Pro dimensions after hiding the sidebar.

## Environment

- Local dev: `localhost:1313`
- Browser: Chrome with DevTools device emulation (iPad Pro)

## Additional context

The sidebar state is stored in `localStorage` under `influxdata_docs_preferences.sidebar_state`. Resizing to desktop width restores the sidebar, but the toggle remains inaccessible at the tablet viewport.

Run the local site at localhost:1313 and reproduce the issue on /influxdb3/core/api/cache-distinct-values/ at approximately 1024x1366 after hiding the sidebar. Trace the sidebar toggle entry point and the localStorage key influxdata_docs_preferences.sidebar_state. Done means the toggle remains visible and can restore the sidebar at tablet widths without resizing.

Written by the indexing model from the issue text.