[Alumos]

Problem

PR #2 and #4 browser checks repeatedly fail in the existing mobile schools flow. The success toast at the top overlaps navigation and may remain paused under the pointer.

Change

• Reuse existing mobile breakpoint hook: bottom-center feedback on mobile, top-right unchanged on desktop.
• Add a close button.
• Add a real school-save toast regression checking navigation while feedback is visible, covering 320/390px and 100/150% UI scale. No force-click, skipped assertions, or added sleeps.

Validation

• Local git diff --check passed.
• Full existing GitHub CI pending; local package/container runtime is not available.
• No release workflow triggered.

Separate prerequisite repair; dependency PRs remain dependency-only.