CI is very unstable lately, getting 404 every other day

```
foundryup: fetching latest nightly release tags from foundry-rs/foundry...
foundryup: resolved nightly release tag: nightly-56b854e401f5748989d346f0aea871bac5d3e266
foundryup: installing foundry (version nightly, tag nightly-56b854e401f5748989d346f0aea871bac5d3e266)
foundryup: checking if forge, cast, anvil, chisel, solar for nightly-56b854e401f5748989d346f0aea871bac5d3e266 version are already installed
foundryup: no attestation found for this release, skipping SHA verification
foundryup: downloading foundry_nightly_linux_amd64.tar.gz
foundryup: foundryup is up to date.
Error:
0: failed to download https://github.com/foundry-rs/foundry/releases/download/nightly-56b854e401f5748989d346f0aea871bac5d3e266/foundry_nightly_linux_amd64.tar.gz: HTTP 404 Not Found
```

Start at foundryup's nightly tag resolution and release download path, using the logged tag and URL to reproduce the 404. Trace how the GitHub Action invokes that installer and verify the release asset is available or the failure is handled consistently; done means CI no longer fails intermittently with this missing nightly asset.

Written by the indexing model from the issue text.