Add Gulf of St. Lawrence Map and Related Flags (#2524)

## Description:

Adds the Gulf of St. Lawrence map and the flags of New Brunswick
(ca_nb), Nova Scotia (ca_ns), and Prince Edward Island (ca_pe).

## 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

<img width="1380" height="1150" alt="Screenshot 2025-11-26 201008"
src="https://github.com/user-attachments/assets/77531058-b429-4c68-b645-a3e59033458b"
/>
<img width="1434" height="1195" alt="Screenshot 2025-11-26 202128"
src="https://github.com/user-attachments/assets/9c3e2bc2-882f-4662-a32b-16e17db852f2"
/>

## Discord username

sehentsin

src/server/MapPlaylist.ts

@@ -37,6 +37,7 @@ const frequency: Partial<Record<GameMapName, number>> = {
   FalklandIslands: 4,
   FaroeIslands: 4,
   GatewayToTheAtlantic: 5,
+  GulfOfStLawrence: 4,
   Halkidiki: 4,
   Iceland: 4,
   Italia: 6,