fix: embed snackbar offset

[cheneyveron]

Description

Adjust the runtime snackbar position when web is running in embed mode.

In embedded LocationPicker flows, snackbars can overlap the bottom action area and cover buttons. This PR moves the snackbar container higher in embed mode while keeping the existing bottom position for normal runtime usage.

How Has This Been Tested?

• test environment:
  • Debian 13 x86_64
  • OpenCloud image: opencloudeu/opencloud:7.2.0-posix-fastpath-20260704, bundled reva
  • Related extension tested with: opencloud-file-archiver@d2d565a
• Unit test:

pnpm test:unit packages/web-runtime/tests/unit/layouts/Application.spec.ts

Result: 1 file passed, 2 tests passed.

• Type Check & Build

pnpm check:types
Result: passed.

pnpm build
Result: passed.

• Manual test:
  • Opened LocationPickerModal in embed mode
  • Triggered snackbar messages while the picker action bar was visible
  • Confirmed snackbars no longer cover the bottom action buttons
  • Confirmed snackbar position remains unchanged outside embed mode
  • Existing features, such as upload, download, preview, and client sync are working.

Types of changes

• Enhancement (a change that doesn't break existing code or deployments)
• Breaking change (a modification that affects current functionality)
• Technical debt (addressing code that needs refactoring or improvements)
• Tests (adding or improving tests)
• Documentation (updates or additions to documentation)
• Maintenance (like dependency updates or tooling adjustments)