CHANGELOG, tornado showcase shot, capture script update

CHANGELOG.md

@@ -0,0 +1,31 @@
+# Changelog
+
+All notable changes to PolyCity are documented here.
+
+## 1.0.0 — initial public release
+
+### Gameplay
+- Procedurally generated island maps with rivers, beaches and forests
+- RCI zoning with demand-driven development and a three-tier density ladder
+- City-wide power grid (coal / solar / wind, coastal wind bonus) with
+  farthest-first brownouts
+- Land value model (services, pollution, waterfront, leisure) driving upgrades
+- Service buildings: police, fire, hospital, school, park, plaza, stadium
+- Pollution-driven fires that spread unless covered by fire stations
+- Tornado disasters that flatten streets into rubble (toggleable)
+- Budget with live tax slider, itemized income/upkeep ledger
+- Happiness, RCI demand bars, milestones up to Megalopolis, quest onboarding
+- Traffic agents flowing along the road network
+- Day/night cycle with lit windows at night
+
+### Systems
+- Autosave plus 3 manual slots, JSON export/import
+- PWA: installable, offline play via service worker
+- Adaptive render resolution for weak GPUs; optional shadows
+- Touch controls: one-finger paint, two-finger orbit/zoom
+
+### Quality
+- 45-assertion engine test suite (pure Node)
+- 40-year economy soak test (11 assertions)
+- Headless browser end-to-end smoke test
+- GitHub Pages workflow + Netlify config for one-click publishing