Enforce that `FilecoinWarmStorageServiceLayout.sol` only has additions

[BigLep]

Done Criteria

1. We have a CI check that ensures FilecoinWarmStorageServiceLayout.sol only has storage slot additions (i.e., increasing numbers, not overriding or changing existing numbers).
2. Release process has an explicit step for human checking that FilecoinWarmStorageServiceLayout.sol has no destructive changes between the current contract release and the to-be-released contract.
3. https://github.com/FilOzone/filecoin-services/blob/main/SPEC.md#cross-cutting-concerns documents this extra check that we're doing.

Why Important

Messing up storage slots in the proxy is one potential way to force us to need to deploy a new proxy, which we want to avoid if at all possible.

User/Customer

Engineering team

1. We are relying on check-gen CI job (.github/workflows/check.yml) runs make gen on every PR/push to main and fails if regenerated output differs from what is committed the build step that invokestools/generate_storage_layout.sh to keep FilecoinWarmStorageServiceLayout.sol updated/current.

[BigLep]

@rjan90 : FYI that I created in response to 2026-03-17 discussion in FOC engineering sync and brainstorm with @rvagg about how to mitigate the change that we need to deploy a new proxy because we shot ourselves in the foot by messing up storage layout.

[Chaitu-Tatipamula]

can i take this up? @BigLep

[Chaitu-Tatipamula]

i can create tools/check_storage_layout.sh which:
- detects removed storage slots
- detects renumbered/reordered slots
- ensures new slots are appended only (slot numbers > previous max)
and then update .github/workflows/check.yml to run this check
add make check-layout target so developers can validate before pushing, finally update the documentation part