Feat: Alliance and betrayal hotkeys (#3110)

Original Feature request by @FloPinguin  
Resolves #3077 

## Description:

Adds hotkeys for Requesting alliances and breaking alliances. This
allows for players to send or break alliances whose tile is under the
cursor, without opening the radial menu.

Keybinds:
New "Ally Keybinds" section in Settings -> Keybinds
Request alliance: Default: K - sends an alliance request to the
player/bot/nation under the cursor
Break alliance: Default: L - breaks the alliance with the player at the
cursor

Behavior:
- Cursor must be over a tile owned by the target player. The action runs
only when the game allows it, following the same logic as the radial
menu. (canSendAllianceRequest and canBreakAlliance)
- When an alliance request is sent, the events log shows: "Alliance
request sent to [target]" for confirmation. No extra message for
breaking an alliance (betrayal/debuff message already exists and is sent
upon breaking an alliance)

## Screenshots:
Keybind menu:
<img width="739" height="595" alt="image"
src="https://github.com/user-attachments/assets/ee958eab-fd50-4971-85c5-dfd49c6f0bdc"
/>
In game logs:
<img width="373" height="232" alt="image"
src="https://github.com/user-attachments/assets/2cf6bb07-5f0d-425a-82d3-65a44fef99c5"
/>

## 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


Discord username:
_Dave9595_

src/core/game/UserSettings.ts

@@ -19,6 +19,8 @@ export function getDefaultKeybinds(isMac: boolean): Record<string, string> {
     attackRatioUp: "KeyY",
     boatAttack: "KeyB",
     groundAttack: "KeyG",
+    requestAlliance: "KeyK",
+    breakAlliance: "KeyL",
     swapDirection: "KeyU",
     zoomOut: "KeyQ",
     zoomIn: "KeyE",