Nations build SAM launchers (#1931)

## Description:

Fixes #201 by adding the ability for nations to build SAM launchers.

<img width="888" height="625" alt="image"
src="https://github.com/user-attachments/assets/b07f1b4e-d022-4674-b842-bc8b4247825d"
/>

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

src/core/execution/FakeHumanExecution.ts

@@ -437,6 +437,7 @@ export class FakeHumanExecution implements Execution {
       this.maybeSpawnStructure(UnitType.Port) ||
       this.maybeSpawnWarship() ||
       this.maybeSpawnStructure(UnitType.Factory) ||
+      this.maybeSpawnStructure(UnitType.SAMLauncher) ||
       this.maybeSpawnStructure(UnitType.MissileSilo)
     );
   }

src/core/execution/SAMLauncherExecution.ts

@@ -50,7 +50,8 @@ class SAMTargetingSystem {
 
   private isInRange(tile: TileRef) {
     const samTile = this.sam.tile();
-    const rangeSquared = this.mg.config().defaultSamRange() ** 2;
+    const range = this.mg.config().defaultSamRange();
+    const rangeSquared = range * range;
     return this.mg.euclideanDistSquared(samTile, tile) <= rangeSquared;
   }
 

src/core/execution/nation/structureSpawnTileValue.ts

@@ -13,24 +13,9 @@ export function structureSpawnTileValue(
   const borderSpacing = mg.config().nukeMagnitudes(UnitType.AtomBomb).outer;
   const structureSpacing = borderSpacing * 2;
   switch (type) {
-    case UnitType.Port:
-      return (tile) => {
-        let w = 0;
-
-        // Prefer to be far away from other structures of the same type
-        const otherTiles: Set<TileRef> = new Set(otherUnits.map((u) => u.tile()));
-        otherTiles.delete(tile);
-        const closestOther = closestTwoTiles(mg, otherTiles, [tile]);
-        if (closestOther !== null) {
-          const d = mg.manhattanDist(closestOther.x, tile);
-          w += Math.min(d, structureSpacing);
-        }
-
-        return w;
-      };
     case UnitType.City:
     case UnitType.Factory:
-    case UnitType.MissileSilo:
+    case UnitType.MissileSilo: {
       return (tile) => {
         let w = 0;
 
@@ -56,6 +41,68 @@ export function structureSpawnTileValue(
         // TODO: Cities and factories should consider train range limits
         return w;
       };
+    }
+    case UnitType.Port: {
+      return (tile) => {
+        let w = 0;
+
+        // Prefer to be far away from other structures of the same type
+        const otherTiles: Set<TileRef> = new Set(otherUnits.map((u) => u.tile()));
+        otherTiles.delete(tile);
+        const closestOther = closestTwoTiles(mg, otherTiles, [tile]);
+        if (closestOther !== null) {
+          const d = mg.manhattanDist(closestOther.x, tile);
+          w += Math.min(d, structureSpacing);
+        }
+
+        return w;
+      };
+    }
+    case UnitType.SAMLauncher: {
+      const protectTiles: Set<TileRef> = new Set();
+      for (const unit of player.units()) {
+        switch(unit.type()) {
+          case UnitType.City:
+          case UnitType.Factory:
+          case UnitType.MissileSilo:
+          case UnitType.Port:
+            protectTiles.add(unit.tile());
+        }
+      }
+      const range = mg.config().defaultSamRange();
+      const rangeSquared = range * range;
+      return (tile) => {
+        let w = 0;
+
+        // Prefer higher elevations
+        w += mg.magnitude(tile);
+
+        // Prefer to be away from the border
+        const closestBorder = closestTwoTiles(mg, borderTiles, [tile]);
+        if (closestBorder !== null) {
+          const d = mg.manhattanDist(closestBorder.x, tile);
+          w += Math.min(d, borderSpacing);
+        }
+
+        // Prefer to be far away from other structures of the same type
+        const otherTiles: Set<TileRef> = new Set(otherUnits.map((u) => u.tile()));
+        otherTiles.delete(tile);
+        const closestOther = closestTwoTiles(mg, otherTiles, [tile]);
+        if (closestOther !== null) {
+          const d = mg.manhattanDist(closestOther.x, tile);
+          w += Math.min(d, structureSpacing);
+        }
+
+        // Prefer to be in range of other structures
+        for (const maybeProtected of protectTiles) {
+          const distanceSquared = mg.euclideanDistSquared(tile, maybeProtected);
+          if (distanceSquared > rangeSquared) continue;
+          w += structureSpacing;
+        }
+
+        return w;
+      };
+    }
     default:
       throw new Error(`Value function not implemented for ${type}`);
   }