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_

resources/lang/en.json

@@ -633,6 +633,11 @@
     "boat_attack_desc": "Send a boat attack to the tile under your cursor.",
     "ground_attack": "Ground Attack",
     "ground_attack_desc": "Send a ground attack to the tile under your cursor.",
+    "ally_keybinds": "Ally Keybinds",
+    "request_alliance": "Request Alliance",
+    "request_alliance_desc": "Send an alliance request to the player whose tile is under your cursor.",
+    "break_alliance": "Break Alliance (Betray)",
+    "break_alliance_desc": "Break alliance with the player whose tile is under your cursor.",
     "swap_direction": "Swap Rocket Direction",
     "swap_direction_desc": "Toggle rocket launch direction (up/down).",
     "zoom_controls": "Zoom Controls",
@@ -818,6 +823,7 @@
     "sent_emoji": "Sent {name}: {emoji}",
     "renew_alliance": "Request to renew",
     "request_alliance": "{name} requests an alliance!",
+    "alliance_request_sent": "Alliance request sent to {name}.",
     "focus": "Focus",
     "accept_alliance": "Accept",
     "reject_alliance": "Reject",