Fixes a black-canvas regression on /map after creating a science in
DEV: when Vite hot-reloads the decoder bump that adds the
`localScience` field, the live in-memory `gameState.report` keeps
its older shape with no such field, so the overlay's
`[...report.localScience]` throws inside the reactive getter and
silently aborts the map view's `$effect`. The fix wraps the spread
and the final return in `?? []` defaults — and matches the
ship-class branches for symmetry — so the overlay stays well-defined
for any partial report shape upstream consumers may carry across an
HMR boundary.
Also adds order-overlay regression tests covering the createScience /
removeScience branches plus the explicit HMR-stale shape, and a
Playwright e2e (sciences-map-regress.spec.ts) replaying the
user-reported flow: /map → /designer/science → save → /map, asserting
no map-mount-error overlay and no console errors.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>