- Add CivilizationCityMap.js: draws the 21-tile fat cross in the city screen
with terrain, specials, city sprite, pips, borders, units, and veiled tiles
- Replace fixed 28-row build list with a scrollable window; add shield cost
and turn-estimate annotations per build choice
- Add garrison display: fortified units shown as clickable roundels
- Refactor tileYield() to accept a `notes` array that records each rule's
delta, enabling accurate tooltips that can never drift from engine math
- Extract paintTerrainDiamond() and specialColor() from CivilizationMapView
so the city map and main map share identical rendering
- Add cityCentreYield() enforcing the 1-shield/1-trade market-economy floor
- Add cityTileStatus() for consistent worked/idle/taken/offmap classification
- Add describeCityTileTooltip() with terrain title, yield breakdown, missing
improvement explanations, and status line
- Wire improvementSheet and iconSheet paths in civilization-artwork.json
- Add comprehensive verifyCivilization checks for yield notes, centre floor,
tile status, tooltips, and build list capacity
