🖼️ Fix broken amwdrizz contributor avatar (#139) (#141)

## Change Log / Overview

🖼️ Fixes the broken `@amwdrizz` avatar in the contributor tables — exactly as described in #139. Straightforward change, so this one should be easy to take or leave.

Swaps the login-based avatar URL for the numeric user id:

```diff
-https://avatars.githubusercontent.com/u/amwdrizz?v=4
+https://avatars.githubusercontent.com/u/1386055?v=4
```

Three lines, one per file:

| File                  | Role                          |
| --------------------- | ----------------------------- |
| `.all-contributorsrc` | source of truth               |
| `README.md`           | generated ALL-CONTRIBUTORS-LIST |
| `CONTRIBUTORS.md`     | generated ALL-CONTRIBUTORS-LIST |

### Why it rendered broken

The `/u/` avatar endpoint expects a numeric id. With a login it doesn't 404 — it **302-redirects to the GitHub homepage**, which returns `text/html`, so the `<img>` had nothing to render:

```
$ curl -sI 'https://avatars.githubusercontent.com/u/amwdrizz?v=4'
HTTP/2 302
location: https://github.com

$ curl -sLo /dev/null -w '%{content_type}\n' 'https://avatars.githubusercontent.com/u/amwdrizz?v=4'
text/html; charset=utf-8
```

After the fix:

```
$ curl -sLo /dev/null -w '%{http_code} %{content_type}\n' 'https://avatars.githubusercontent.com/u/1386055?v=4'
200 image/png
```

Id confirmed via `gh api users/amwdrizz` → `1386055`, which matches the value suggested in the issue.

### Note on regeneration

The issue suggested re-running all-contributors. I hand-edited the two generated blocks instead so the diff stays at three lines — running the CLI would have been equivalent here but risked reflowing unrelated table markup. Happy to regenerate properly instead if you'd prefer the tables stay tool-managed.

Docs-only change: no source, tests, or version touched. `prettier --check` passes and `.all-contributorsrc` still parses as valid JSON.

## Related Issues, Builds, Pipeline Runs, etc.

- #139

## Pull Request Pre-check

- [ ] Linting Validation Passed — n/a, no source files changed
- [x] Formatting Validation Passed
- [ ] Unit Testing Passes — n/a, no source files changed
- [x] Documentation Updated