feat: Add keepMounted param to TabPanels for persisting panels when they are not active

[mattrunyon]

Part of DH-18349. Will need a small update in dh.ui to enable support there which is what the ticket wants.

Does not change default behavior of TabPanels, just adds an extra param to keep static panels mounted (in React, but not actually mounted in the DOM).

There are unit tests, but can also test with local plugins from this PR deephaven/deephaven-plugins#1177

[Copilot]

Pull Request Overview

This PR introduces a new keepMounted prop to TabPanels that allows static panels to persist their component state when not active. The changes include re-exporting the new DHCTabPanels component, implementing the keepMounted logic within TabPanels, and adding unit tests to verify both persistent and non-persistent behaviors.

Reviewed Changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated no comments.

File	Description
packages/components/src/spectrum/navigation.ts	Re-exports DHCTabPanels in place of Spectrum TabPanels
packages/components/src/spectrum/TabPanels.tsx	Implements keepMounted support using portal nodes
packages/components/src/spectrum/TabPanels.test.tsx	Adds tests validating both keepMounted and default behavior

Files not reviewed (1)

• packages/components/package.json: Language not supported

[codecov]

Codecov Report

Attention: Patch coverage is 86.48649% with 5 lines in your changes missing coverage. Please review.

Project coverage is 47.10%. Comparing base (6d65594) to head (b0192bc).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/components/src/spectrum/TabPanels.tsx	86.48%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2434      +/-   ##
==========================================
+ Coverage   47.06%   47.10%   +0.03%     
==========================================
  Files         714      715       +1     
  Lines       39468    39505      +37     
  Branches    10063     9884     -179     
==========================================
+ Hits        18576    18608      +32     
- Misses      20881    20886       +5     
  Partials       11       11              

Flag	Coverage Δ
unit	47.10% <86.48%> (+0.03%)	⬆️

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[Copilot]

Pull Request Overview

This PR adds a new keepMounted prop to the TabPanels component to enable persistent mounting of static panels. The changes include updating the navigation export to point to the new DHCTabPanels, implementing the DHCTabPanels component with portal logic to conditionally keep panels mounted, and adding unit tests covering both default and keepMounted behaviors.

Reviewed Changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

File	Description
packages/components/src/spectrum/navigation.ts	Updates export to wrap TabPanels with the new DHCTabPanels component.
packages/components/src/spectrum/TabPanels.tsx	Introduces DHCTabPanels with portal management for persisting panels.
packages/components/src/spectrum/TabPanels.test.tsx	Adds tests to verify both default and keepMounted behaviors.

Files not reviewed (1)

• packages/components/package.json: Language not supported

Comments suppressed due to low confidence (1)

packages/components/src/spectrum/TabPanels.test.tsx:194

• [nitpick] Consider awaiting the waitFor call (e.g., using 'await waitFor(...)' in an async test) to ensure asynchronous assertions complete reliably.

waitFor(() => expect(onMount).toHaveBeenCalledTimes(1));

[mattrunyon]

Found a potential (although probably extremely unlikely to happen) leak if using different keys to add new panels.

Added a test to ensure components unmount if they aren't in the actual panel any more.