fix(projects): show create menu when no projects exist

[mijanx]

Summary

Problem

On a relay with zero projects, the Projects view returned the No projects yet empty state before rendering the normal Projects shell. That shell contains the only project-creation affordance: the + create menu.

This created a chicken-and-egg failure: users could not create their first project from the desktop UI because the create button only appeared after at least one project already existed. Creating a project out-of-band made the button appear.

Implementation

• Keep the normal Projects header, navigation, and + create menu mounted when the project list is empty.
• Render the existing No projects yet state inside the shell's content area instead of returning it as the entire view.
• Add an E2E-only zero-project fixture and a regression test that verifies the empty state still exposes the create menu and opens the New Project dialog.
• Leave loading, error, filtered, and non-empty rendering behavior unchanged.

No follow-up work is deferred.

Related issue

Fixes #3504. Also addresses #2585 and #2622.

Testing

• pnpm --dir desktop exec playwright test tests/e2e/project-commit-detail.spec.ts --project=smoke -g "empty projects state keeps project creation available"
  • 1 passed
• just ci
  • Passed
• Manual/E2E verification:
  1. Start with no project events.
  2. Open Projects and confirm No projects yet is shown.
  3. Confirm the top-right + button is visible.
  4. Open it, select Project, and confirm the New Project dialog opens.

Before

With zero projects, only the empty state rendered. There was no Projects header, toolbar, or + button, so the first project could not be created from the UI.

After

The standard Projects shell remains visible around the same empty state. The + menu is available and exposes Project, allowing creation of the first project.