bug: StatsSchema zod validation error (#1267)

## Description:

Fix a bug in the StatsSchema zod validation logic. In zod v4, the
`record` function has been renamed to `partialRecord`, and the new
`record` function requires that all keys are present. We intentionally
omit empty stats, so this causes a zod validation error.

Example error:

```
Connection error!
 game id: VSEtmKpJ, client id: 0UMrA84F
Error: ✖ Invalid input: expected array, received undefined
  → at allPlayersStats.0UMrA84F.units.wshp
✖ Invalid input: expected array, received undefined
  → at allPlayersStats.0UMrA84F.units.saml
Stack: 
```

## 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
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

src/core/StatsSchemas.ts

@@ -98,10 +98,10 @@ export const PlayerStatsSchema = z
   .object({
     attacks: AtLeastOneNumberSchema.optional(),
     betrayals: BigIntStringSchema.optional(),
-    boats: z.record(BoatUnitSchema, AtLeastOneNumberSchema).optional(),
-    bombs: z.record(BombUnitSchema, AtLeastOneNumberSchema).optional(),
+    boats: z.partialRecord(BoatUnitSchema, AtLeastOneNumberSchema).optional(),
+    bombs: z.partialRecord(BombUnitSchema, AtLeastOneNumberSchema).optional(),
     gold: AtLeastOneNumberSchema.optional(),
-    units: z.record(OtherUnitSchema, AtLeastOneNumberSchema).optional(),
+    units: z.partialRecord(OtherUnitSchema, AtLeastOneNumberSchema).optional(),
   })
   .optional();
 export type PlayerStats = z.infer<typeof PlayerStatsSchema>;