Set a targetable status for nukes (#1174)

## Description:

Set a targetable status for units (specifically atom bomb and hydro)
A nuke is targetable near launch and target but is untargetable mid air.
An untargetable unit is half transparent to show that it cannot be
destroyed.


![targetable](https://github.com/user-attachments/assets/cc6769ff-95ab-4294-9a8e-10f909711f68)

## 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
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

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

Vivacious Box

src/core/game/Game.ts

@@ -383,6 +383,8 @@ export interface Unit {
   targetedBySAM(): boolean;
   setReachedTarget(): void;
   reachedTarget(): boolean;
+  isTargetable(): boolean;
+  setTargetable(targetable: boolean): void;
 
   // Health
   hasHealth(): boolean;

src/core/game/GameUpdates.ts

@@ -76,6 +76,7 @@ export interface UnitUpdate {
   isActive: boolean;
   reachedTarget: boolean;
   retreating: boolean;
+  targetable: boolean;
   targetUnitId?: number; // Only for trade ships
   targetTile?: TileRef; // Only for nukes
   health?: number;

src/core/game/GameView.ts

@@ -72,6 +72,10 @@ export class UnitView {
     return this.data.id;
   }
 
+  targetable(): boolean {
+    return this.data.targetable;
+  }
+
   type(): UnitType {
     return this.data.unitType;
   }

src/core/game/UnitImpl.ts

@@ -30,6 +30,8 @@ export class UnitImpl implements Unit {
   private _readyMissileCount: number = 1;
   private _patrolTile: TileRef | undefined;
   private _level: number = 1;
+  private _targetable: boolean = true;
+
   constructor(
     private _type: UnitType,
     private mg: GameImpl,
@@ -63,6 +65,17 @@ export class UnitImpl implements Unit {
     }
   }
 
+  setTargetable(targetable: boolean): void {
+    if (this._targetable !== targetable) {
+      this._targetable = targetable;
+      this.mg.addUpdate(this.toUpdate());
+    }
+  }
+
+  isTargetable(): boolean {
+    return this._targetable;
+  }
+
   setPatrolTile(tile: TileRef): void {
     this._patrolTile = tile;
   }
@@ -101,6 +114,7 @@ export class UnitImpl implements Unit {
       reachedTarget: this._reachedTarget,
       retreating: this._retreating,
       pos: this._tile,
+      targetable: this._targetable,
       lastPos: this._lastTile,
       health: this.hasHealth() ? Number(this._health) : undefined,
       constructionType: this._constructionType,