Rewrite geography-demos, demo-interactions, and reactive-nav specs
to use 300-500ms waits instead of 2-3s sleeps. Each test still does
a fresh page.goto() for isolation (no knock-on failures) but benefits
from server response cache for near-instant page loads.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>