fix(app): auto-register direct-route projects

[wxt365]

Issue for this PR

Closes #18943

Type of change

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

What does this PR do?

Opening a valid /:dir/... route resolved the directory context, but it did not register the project in the sidebar.

This PR triggers the existing project-open flow after the direct-route directory is resolved, so direct routing behaves the same as manually opening a project.

The change is small and reuses the existing idempotent layout.projects.open() path, which already loads sessions and avoids duplicate sidebar entries.

How did you verify your code works?

• cd packages/app && bun test --preload ./happydom.ts ./src/pages/directory-layout.test.ts
• cd packages/app && bun test

Screenshots / recordings

Attach a short recording showing that opening /{base64(directory)}/session makes the project appear in the sidebar automatically.

Checklist

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

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential duplicate found:

• PR fix(app): open project when navigating directly to a project URL #16838: fix(app): open project when navigating directly to a project URL
  • This PR appears to address a similar issue: opening/registering projects when navigating directly to a project URL. Current PR fix(app): auto-register direct-route projects #18947 specifically handles the direct-route registration in the sidebar, which may be related to or build upon the direct project URL navigation feature.