Implement donation troops/gold between human players after forming an alliance (#2450)

Resolves #2448 

Hi team,

I've implemented and locally tested the alliance-related changes
(including unit tests and some manual simulation with multiple browser
profiles).
Unfortunately I wasn't able to perform full end-to-end testing on the
live game server with two separate machines/accounts.

If someone on the team (or another contributor) can verify the alliance
flow with two real players, that would be greatly appreciated before
merging. Happy to hop on a call or provide any clarification needed.

Thanks!

## Description:

Fixed a race condition bug where donations (troops/gold) between human
players failed after forming an alliance. The issue was caused by a
one-tick delay in `AllianceRequestReplyExecution`: the alliance
acceptance logic ran in `tick()` instead of `init()`, meaning the
alliance wasn't created until the tick after the execution was added. If
a donation execution was added in the same turn as the alliance
acceptance, it would fail the `isFriendly()` check because the alliance
didn't exist yet.

**Root cause:** When human players formed alliances via reply, the
execution model delayed alliance creation by one tick, while bots called
`accept()` directly without this delay.

**Solution:** Moved alliance acceptance logic from `tick()` to `init()`
in `AllianceRequestReplyExecution.ts`, ensuring immediate alliance
creation and eliminating race conditions with donations.

**Changes:**
- Modified
`src/core/execution/alliance/AllianceRequestReplyExecution.ts` to
process alliance replies in `init()` instead of `tick()`
- Added comprehensive test suite `tests/AllianceDonation.test.ts` with 5
test cases covering donation scenarios after alliance formation (reply
and mutual request flows)
- All existing tests pass (323 total)

## Please complete the following:

- [x] I have added screenshots for all UI updates (N/A - backend logic
fix only)
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file (N/A - no user-facing text
changes)
- [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


Discord: loacky
GitHub: @LoackyBit

---------

Co-authored-by: Evan <evanpelle@gmail.com>

src/core/execution/alliance/AllianceRequestReplyExecution.ts

@@ -19,12 +19,7 @@ export class AllianceRequestReplyExecution implements Execution {
       return;
     }
     this.requestor = mg.player(this.requestorID);
-  }
 
-  tick(ticks: number): void {
-    if (this.requestor === null) {
-      throw new Error("Not initialized");
-    }
     if (this.requestor.isFriendly(this.recipient)) {
       console.warn("already allied");
     } else {
@@ -46,6 +41,8 @@ export class AllianceRequestReplyExecution implements Execution {
     this.active = false;
   }
 
+  tick(ticks: number): void {}
+
   isActive(): boolean {
     return this.active;
   }