Increase spawn immunity from 30s to 45s for 5M starting gold maps 🛡️ (#3457)

## Description:

Increases the spawn immunity duration from 30s to 45s for maps with 5M
starting gold.

The previous 30s was too short - 45s gives players 15s longer than it
takes to build a SAM, allowing them to establish basic defenses before
becoming vulnerable.

## 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/configuration/DefaultConfig.ts

@@ -136,6 +136,9 @@ export abstract class DefaultServerConfig implements ServerConfig {
   }
 }
 
+/** SAM launcher construction duration in ticks (non-instant-build). */
+export const SAM_CONSTRUCTION_TICKS = 30 * 10;
+
 export class DefaultConfig implements Config {
   private pastelTheme: PastelTheme = new PastelTheme();
   private pastelThemeDark: PastelThemeDark = new PastelThemeDark();
@@ -430,7 +433,9 @@ export class DefaultConfig implements Config {
               Math.min(3_000_000, (numUnits + 1) * 1_500_000),
             UnitType.SAMLauncher,
           ),
-          constructionDuration: this.instantBuild() ? 0 : 30 * 10,
+          constructionDuration: this.instantBuild()
+            ? 0
+            : SAM_CONSTRUCTION_TICKS,
           upgradable: true,
         };
         break;