Test: regression coverage for the 'N notes loading…' sidebar banner

[thetechjon]

Context

When a fresh user clones a vault, note bodies stream in progressively (the sidebar tree shows note titles immediately; bodies arrive in the background). While bodies are still loading, the sidebar shows a subtle "N notes loading…" banner driven by counting notes with contentLoaded === false. This is a feature the maintainer asked to keep visible after it regressed in an earlier refactor.

A regression test would lock it in so the banner cannot silently disappear again.

Where to look

• src/components/sidebar/FolderTree.tsx lines 102-110 — shellCount calculation; the banner JSX is in the same component, search for loading in the file.
• src/__tests__/ — existing component tests use @testing-library/react (see e.g. src/__tests__/markdownLivePreview.test.ts or other tests for the pattern).

Acceptance criteria

• New test file src/__tests__/folderTreeLoadingBanner.test.tsx (or extend an existing FolderTree test).
• Test 1: render FolderTree with 3 notes, 2 of them contentLoaded: false. Assert the banner is in the DOM and shows the right count.
• Test 2: render with all notes contentLoaded: true. Assert the banner is NOT in the DOM.
• Test 3: render with 0 notes. Assert the banner is NOT in the DOM (empty vault case).

Complexity

Tiny. Good first PR if you have never touched React testing before.

For first-time contributors

Read CONTRIBUTING.md. npm install then npm test to confirm the suite passes locally before you start. The existing tests under src/__tests__/ are the best reference for the patterns the codebase uses. PR against dev.