Prevent AI from placing ports on small lakes 🚢 (#4429)

## Description:

AI nations were placing ports on small decorative ponds scattered across
maps (Missisipi for example), wasting structure slots on strategically
useless water bodies. This fix adds a water component size check to the
port placement logic so the AI skips lakes that are too small for
meaningful port use. We already had a check for available trade
partners, but trading in small lakes is usually stupid.

**How it works:**
- `ConnectedComponents` now tracks component sizes during its existing
flood-fill (zero extra cost - counts tiles as they're visited)
- `AbstractGraph`, `WaterManager`, and the `Game` interface expose
`getWaterComponentSize(tile)` so callers can query the size of any water
body
- `NationStructureBehavior.randCoastalTileArray()` filters out non-ocean
water components below `MIN_PORT_WATER_COMPONENT_SIZE` (3000 minimap
tiles, ~12000 full-map tiles)
- Ocean tiles bypass the check entirely since they're always large
enough

## 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

## Please put your Discord username so you can be contacted if a bug or
regression is found:

FloPinguin

src/core/game/Game.ts

@@ -799,6 +799,12 @@ export interface Game extends GameMap {
   miniWaterGraph(): AbstractGraph | null;
   getWaterComponent(tile: TileRef): number | null;
   hasWaterComponent(tile: TileRef, component: number): boolean;
+  /**
+   * Returns the approximate number of water tiles in the component
+   * containing `tile`, or null if the tile has no water component. Useful for
+   * filtering tiny water bodies (e.g. preventing AI port placement on ponds).
+   */
+  getWaterComponentSize(tile: TileRef): number | null;
   /**
    * Returns the set of water components that `player` shares with at least one
    * valid trade partner (cached). Used by nation AI for port-placement

src/core/game/GameImpl.ts

@@ -1204,6 +1204,9 @@ export class GameImpl implements Game {
   hasWaterComponent(tile: TileRef, component: number): boolean {
     return this._waterManager.hasWaterComponent(tile, component);
   }
+  getWaterComponentSize(tile: TileRef): number | null {
+    return this._waterManager.getWaterComponentSize(tile);
+  }
   sharedWaterComponents(player: Player): Set<number> | null {
     return this._sharedWaterCache.get(player);
   }

src/core/game/WaterManager.ts

@@ -182,6 +182,21 @@ export class WaterManager {
     return false;
   }
 
+  /**
+   * Returns the approximate number of water tiles in the component
+   * containing `tile`, or null if the tile has no water component.
+   *
+   * The underlying ConnectedComponents are computed on the 2× downsampled
+   * minimap, so each minimap tile represents up to 4 full-map tiles.  We
+   * multiply by 4 to give callers a value in full-map-tile units.
+   */
+  getWaterComponentSize(tile: TileRef): number | null {
+    const componentId = this.getWaterComponent(tile);
+    if (componentId === null) return null;
+    if (!this._miniWaterGraph) return 0;
+    return this._miniWaterGraph.getComponentSize(componentId) * 4;
+  }
+
   private finalizeWaterChanges(
     convertedTiles: TileRef[],
     changedTiles: TileRef[],