fix(frontend): await the render in the LeafletLayers tests

[JuliusHenke]

What

renderLayers in LeafletLayers.test.tsx called renderWithProviders(...) without awaiting it and returned {screen, reloadSelectedDay}. await renderLayers(...) therefore awaited a plain object and never waited for the render. When a CI runner was slow, the render could finish after the test (or the cleanup) had moved on and fail as an unhandled rejection, which fails the whole run:

Unhandled Rejection
TypeError: Cannot read properties of undefined (reading 'includes')
 ❯ Object.render ... vitest-browser-react
The last test to run before this error was "selects a family directly when it is alone at its location"

Seen in the "Frontend Push" run of #609 (a firebase.json-only change), while "Frontend Pull Request" passed for the very same commit.

Fix

renderLayers is now async and awaits the render. No production code changes.

Verification

tsc, eslint and yarn test:coverage (3 runs, 244 tests, no errors). I could not reproduce the failure locally before the change either (4 runs), as it depends on runner speed, so this is the most likely cause rather than a reproduced one. If the error shows up again after this, the next suspect is the lazy dialogs finishing after cleanup.

Dependencies / deployment

None.

🤖 Generated with Claude Code

[github-actions]

Visit the preview URL for this PR (updated for commit 5c618ea):

https://tormap-36f44--pr610-fix-frontend-await-l-w10rlgek.web.app

_{(expires Wed, 11 Nov 2026 17:39:08 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

_{Sign: 0c1f71965de18e60b0e686b0d0356977fec090dc}