Use bigint for gold (#1000)

## Description:

- Switch gold to bigint.
- Remove unused or untrusted values from event payloads.

## 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

---------

Co-authored-by: Scott Anderson <662325+scottanderson@users.noreply.github.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

src/core/game/Game.ts

@@ -12,7 +12,7 @@ import { Stats } from "./Stats";
 
 export type PlayerID = string;
 export type Tick = number;
-export type Gold = number;
+export type Gold = bigint;
 
 export const AllPlayers = "AllPlayers" as const;
 
@@ -450,7 +450,7 @@ export interface Player {
   troops(): number;
   targetTroopRatio(): number;
   addGold(toAdd: Gold): void;
-  removeGold(toRemove: Gold): void;
+  removeGold(toRemove: Gold): Gold;
   addWorkers(toAdd: number): void;
   removeWorkers(toRemove: number): void;
   setTargetTroopRatio(target: number): void;
@@ -506,8 +506,8 @@ export interface Player {
 
   // Donation
   canDonate(recipient: Player): boolean;
-  donateTroops(recipient: Player, troops: number): void;
-  donateGold(recipient: Player, gold: number): void;
+  donateTroops(recipient: Player, troops: number): boolean;
+  donateGold(recipient: Player, gold: Gold): boolean;
 
   // Embargo
   hasEmbargoAgainst(other: Player): boolean;
@@ -619,7 +619,7 @@ export interface PlayerActions {
 export interface BuildableUnit {
   canBuild: TileRef | false;
   type: UnitType;
-  cost: number;
+  cost: Gold;
 }
 
 export interface PlayerProfile {