Feature Request: Cache fetched source code during on-chain fuzzing for reuse in subsequent runs

### Describe the desired feature

```
Fetching source for 0x14716C982Fd8b7F1E8F0c4dbb496dCe438a29D93 from Sourcify... Success!
```

This now happens after every run, which is a lot when debugging. It would be great if we can cache this.

Start by locating the Sourcify source-fetch path and the lifecycle of on-chain fuzzing runs. Implement reuse of fetched source data across subsequent runs so the same address is not fetched every time, then verify the behavior by repeating a run that previously triggered the fetch.

Written by the indexing model from the issue text.