fix(app): prevent stale session tab reads

[OpeOginni]

Issue for this PR

Closes #39766
Closes #39704

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Session and project navigation could update titlebar content while Solid was transitioning away from the previous view. Several callback-form <Show> components exposed guarded accessors to titlebar avatars and portals, allowing their children to read those accessors after the conditions were disposed and crash the desktop renderer with Stale read from <Show>.

This keys those <Show> boundaries and passes their captured values directly to the avatar, portals, and keybind. The titlebar children now receive stable values during teardown instead of reading disposed narrowing accessors.

How did you verify your code works?

• Reproduced the original crash on desktop 1.18.10 by opening an existing session from another project.
• Confirmed the original session-tab crash no longer occurs.
• Ran bun typecheck in packages/app.
• Ran bun test --conditions=browser --preload ./happydom.ts ./test-browser/solid-router-cleanup.test.ts in packages/app.
• The repository commit-hook typecheck completed successfully across 30 packages.
• Ran git diff --check.

Screenshots / recordings

Not applicable; this fixes renderer crashes without changing the UI.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[OpeOginni]

Haha, thanks for the Merge Brendan, but I wasnt completely done with the fix, slept off lol.

Ill make a new one now