Internal classes cannot be reloaded.

If I am reading the history correctly, it seems like back in 2023 there was a fix to allow reloading internal classes. However, I am receiving "inaccessible due to its protection level" errors whenever I make a change to an internal class:

```
FSR: Error when updating files: 'HUDShipUpgradeButton.cs', System.Exception: Compiler failed to produce the assembly. Output: 'C:\Users\USER\AppData\Local\Temp\c9921ed0d75d4fee849e038c879c696c.SourceCodeCombined.cs(27,206): error CS0122: 'HUDUpgradeButton' is inaccessible due to its protection level

C:\Users\USER\AppData\Local\Temp\c9921ed0d75d4fee849e038c879c696c.SourceCodeCombined.cs(29,17): error CS0122: 'ShipUnitBehaviour' is inaccessible due to its protection level

C:\Users\USER\AppData\Local\Temp\c9921ed0d75d4fee849e038c879c696c.SourceCodeCombined.cs(31,18): error CS0122: 'ShipUnitBehaviour' is inaccessible due to its protection level'
```

Start by reproducing the reload failure from HUDShipUpgradeButton.cs and inspect the FastScriptReload path that combines and compiles the changed source. Trace how internal classes such as HUDUpgradeButton and ShipUnitBehaviour are handled, then verify that editing an internal class reloads without CS0122 protection-level errors.

Scritto dal modello di indicizzazione a partire dal testo della issue.