feat(civilization): add steampunk city theme and caravan diplomacy

- Add steampunk city sheet asset configuration
- Reassign Victor and other opponents to steampunk city theme
- Enable wheel scrolling on city choices list
- Allow non-combat units (e.g., caravans) to enter enemy cities
- Block movement into enemy cities when at war

data/civilization-artwork.json

@@ -16,6 +16,7 @@
   "citySheets": {
     "classic": { "key": "civilization-cities-classic", "path": "assets/images/civilization/civilization-cities-classic.png", "frameWidth": 128, "frameHeight": 96 },
     "cyberpunk": { "key": "civilization-cities-cyberpunk", "path": "assets/images/civilization/civilization-cities-cyberpunk.png", "frameWidth": 128, "frameHeight": 96 },
-    "japanese": { "key": "civilization-cities-japanese", "path": "assets/images/civilization/civilization-cities-japanese.png", "frameWidth": 128, "frameHeight": 96 }
+    "japanese": { "key": "civilization-cities-japanese", "path": "assets/images/civilization/civilization-cities-japanese.png", "frameWidth": 128, "frameHeight": 96 },
+    "steampunk": { "key": "civilization-cities-steampunk", "path": "assets/images/civilization/civilization-cities-steampunk.png", "frameWidth": 128, "frameHeight": 96 }
   }
 }

data/opponents.json

@@ -89,7 +89,7 @@
       "name": "Victor",
       "trait": "pioneering",
       "startingTechs": [],
-      "citySheet": "cyberpunk",
+      "citySheet": "steampunk",
       "bio": "Patient and calculating. Moves are made using ancient technology.",
       "voice": "Starfield - Vasco",
       "convo": [
@@ -968,7 +968,7 @@
         "ceremonialburial",
         "horsebackriding"
       ],
-      "citySheet": "classic",
+      "citySheet": "steampunk",
       "bio": "Ahoy you land lovers!",
       "voice": "Defiant Calder",
       "convo": [
@@ -1010,7 +1010,7 @@
         "pottery",
         "thewheel"
       ],
-      "citySheet": "classic",
+      "citySheet": "steampunk",
       "bio": "Bucky Beaver and I are there to TRAP all the fun and games!",
       "speech": {
         "intro": [

src/games/civilization/CivilizationCityScreen.js

@@ -393,6 +393,11 @@ export function openCityScreen(scene, rules, state, city, onClose) {
         Logic.setBuild(rules, state, city, ch.type, ch.id);
         redraw();
       });
+      rect.on('wheel', (pointer, _dx, dy) => {
+        scrollY = Phaser.Math.Clamp(scrollY + dy * 0.5, 0, maxScroll);
+        tooltip.hide();
+        syncRows();
+      });
       tooltip.attachTo(rect, () => {
         if (ch.type === 'unit') return describeUnitTooltip(rules, ch.ruleObj);
         if (ch.type === 'building') return describeBuildingTooltip(rules, ch.ruleObj);
@@ -423,7 +428,7 @@ export function openCityScreen(scene, rules, state, city, onClose) {
       if (thumb) thumb.y = listY + (listH - thumbH) * (scrollY / maxScroll);
     };
     listBg.setInteractive();
-    listBg.on('wheel', (pointer, dx, dy) => {
+    listBg.on('wheel', (pointer, _dx, dy) => {
       scrollY = Phaser.Math.Clamp(scrollY + dy * 0.5, 0, maxScroll);
       // A row disabled mid-hover never fires pointerout, so its tooltip would
       // hang around over the list.

src/games/civilization/CivilizationLogic.js

@@ -916,7 +916,8 @@ export function tryMove(rules, state, unit, dx, dy) {
   }
 
   if (!canOccupy(rules, state, unit, tx, ty)) return { result: 'invalid' };
-  if (targetCity && targetCity.civ !== unit.civ) return { result: 'invalid' };
+  if (targetCity && targetCity.civ !== unit.civ && !def.flags.includes('caravan')) return { result: 'invalid' };
+  if (targetCity && targetCity.civ !== unit.civ && state.civs[unit.civ].relations[targetCity.civ] === 'war') return { result: 'invalid' };
 
   const cost = moveCost(rules, state, unit, unit.x, unit.y, tx, ty);
   if (!Number.isFinite(cost)) return { result: 'invalid' };