For v30: Add new modifiers (Hard nations and 25M Starting Gold) 🙂 (#3316)

## Description:

Adds two new public game modifiers for variety and improves compact map
eligibility for team games.

### New Modifiers

**Hard Nations (`isHardNations`)**
- We need this modifier for HvN, because medium nations are easier now
(will result in a much higher human winrate)
- In a discord discussion we concluded that HvN should generally be
easier (higher winrate than 50%, so players are less frustated)
- Thats why only 20% of HvN games have the hard nations modifier (for
now)
- For PvPvE enjoyers, the modifier is also active in FFA games => (Only
2.5% chance, and 1 ticket in `SPECIAL_MODIFIER_POOL`)

**25M Starting Gold (`startingGoldHigh`)**
- Some people in the main discord wanted this modifier, and it will
result in crazy games
- Rare special-only modifier (1 ticket in pool); mutually exclusive with
5M starting gold via `MUTUALLY_EXCLUSIVE_MODIFIERS`
- Disables nations (they lack PVP immunity, so 25M gold doesn't work
well with them)
- Excluded from HumansVsNations games (since it disables nations)
- Spawn immunity set to **2 minutes 30 seconds** (vs 30s for 5M gold),
so people can spend the gold and prepare

### Other Changes

- **Improved `supportsCompactMapForTeams`**: Replaced the hard `smallest
>= 50` land-tile cutoff with a per-team-config calculation that
simulates worst-case compact player count and checks every team gets at
least 2 players.
- **HvN spawn immunity**: Always 5 seconds in both regular and special
lobbies (to get rid of a confusing PVP immunity HeadsUpMessage in 5M
starting gold games)
- **Regular public lobby random spawn modifier probabilty**: Reduced
from 10% to 5% (Because of the new modifier, so there aren't too many
modifiers in non-special-lobbies, should only occur sometimes there)
- Rebalanced `SPECIAL_MODIFIER_POOL` a bit

## 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:

FloPinguin

src/core/Schemas.ts

@@ -215,6 +215,7 @@ export const GameConfigSchema = z.object({
       isCompact: z.boolean(),
       isRandomSpawn: z.boolean(),
       isCrowded: z.boolean(),
+      isHardNations: z.boolean(),
       startingGold: z.number().int().min(0).optional(),
     })
     .optional(),

src/core/game/Game.ts

@@ -236,6 +236,7 @@ export interface PublicGameModifiers {
   isCompact: boolean;
   isRandomSpawn: boolean;
   isCrowded: boolean;
+  isHardNations: boolean;
   startingGold?: number;
 }