Adds map "The Straits" (#3896)

## Description:

**Adds "The Straits" map:**

A map located around Denmark and the many surrounding straits: Kattegat,
Skagerrak and the Danish straits (thus the name, meant to be a creative
name like "Between Two Seas" and "Gateway to the Atlantic"). This map is
themed in the early 1900s, the nations/NPCs are traditional and
historical regions of Sweden-Norway, Denmark and the Germany.

Relatively small map with ~700k land tiles, similar to World

Inspired by this Discord thread with nearly 20 upvotes:
https://canary.discord.com/channels/1284581928254701718/1482089104110911634/1482089104110911634

<img width="365" height="506" alt="image"
src="https://github.com/user-attachments/assets/5ee16218-34c0-4b8b-9f9b-d33f219760b0"
/>

## 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

## Please put your Discord username so you can be contacted if a bug or
regression is found:

tri.star1011

map-generator/assets/maps/thestraits/info.json

@@ -0,0 +1,136 @@
+{
+  "name": "thestraits",
+  "nations": [
+    {
+      "coordinates": [37, 227],
+      "name": "Agder",
+      "flag": "Sweden Norway Union"
+    },
+    {
+      "coordinates": [252, 43],
+      "name": "Østlandet",
+      "flag": "Sweden Norway Union"
+    },
+    {
+      "coordinates": [737, 791],
+      "name": "Skåne",
+      "flag": "Sweden Norway Union"
+    },
+    {
+      "coordinates": [646, 566],
+      "name": "Halland",
+      "flag": "Sweden Norway Union"
+    },
+    {
+      "coordinates": [846, 488],
+      "name": "Småland",
+      "flag": "Sweden Norway Union"
+    },
+    {
+      "coordinates": [701, 260],
+      "name": "Västergötland",
+      "flag": "Sweden Norway Union"
+    },
+    {
+      "coordinates": [501, 273],
+      "name": "Bohuslän",
+      "flag": "Sweden Norway Union"
+    },
+    {
+      "coordinates": [843, 278],
+      "name": "Östergötland",
+      "flag": "Sweden Norway Union"
+    },
+    {
+      "coordinates": [579, 45],
+      "name": "Dalsland",
+      "flag": "Sweden Norway Union"
+    },
+    {
+      "coordinates": [833, 73],
+      "name": "Närke",
+      "flag": "Sweden Norway Union"
+    },
+    {
+      "coordinates": [510, 821],
+      "name": "Zealand",
+      "flag": "dk"
+    },
+    {
+      "coordinates": [495, 949],
+      "name": "Lolland-Falster",
+      "flag": "dk"
+    },
+    {
+      "coordinates": [347, 862],
+      "name": "Funen",
+      "flag": "dk"
+    },
+    {
+      "coordinates": [239, 976],
+      "name": "Schleswig-Holstein",
+      "flag": "prussia"
+    },
+    {
+      "coordinates": [585, 1182],
+      "name": "Mecklenburg-Schwerin",
+      "flag": "German Empire"
+    },
+    {
+      "coordinates": [846, 1131],
+      "name": "Pomerania",
+      "flag": "prussia"
+    },
+    {
+      "coordinates": [59, 1201],
+      "name": "Oldenburg",
+      "flag": "German Empire"
+    },
+    {
+      "coordinates": [302, 1143],
+      "name": "Hamburg",
+      "flag": "German Empire"
+    },
+    {
+      "coordinates": [219, 1205],
+      "name": "Hanover",
+
+      "flag": "prussia"
+    },
+    {
+      "coordinates": [324, 457],
+      "name": "North Jutland",
+      "flag": "dk"
+    },
+    {
+      "coordinates": [202, 609],
+      "name": "Viborg",
+      "flag": "dk"
+    },
+    {
+      "coordinates": [384, 644],
+      "name": "Aarhus",
+      "flag": "dk"
+    },
+    {
+      "coordinates": [150, 767],
+      "name": "Ringkobing",
+      "flag": "dk"
+    },
+    {
+      "coordinates": [189, 863],
+      "name": "Ribe",
+      "flag": "dk"
+    },
+    {
+      "coordinates": [278, 739],
+      "name": "Vejle",
+      "flag": "dk"
+    },
+    {
+      "coordinates": [850, 889],
+      "name": "Bornholm",
+      "flag": "dk"
+    }
+  ]
+}

map-generator/main.go

@@ -90,6 +90,7 @@ var maps = []struct {
 	{Name: "svalmel"},
 	{Name: "taiwanstrait"},
 	{Name: "thebox"},
+	{Name: "thestraits"},
 	{Name: "tourney1"},
 	{Name: "tourney2"},
 	{Name: "tourney3"},