test: remove stale Fanout corpus project

[vishr]

Summary

Remove the Fanout project from the generic Onebox compatibility corpus and update the frozen contract verdict accordingly.

Why

The fixture was being mistaken for a deployable production definition, but it is stale and unsuitable as a generic Onebox contract case:

• it uses obsolete, non-FANOUT_ environment names that current Fanout ignores
• it declares a custom otlp entrypoint while the managed proxy publishes only ports 80 and 443
• it mixes Fanout product, site, demo, production domains, and deployment policy into Onebox test data
• it cannot render independently because its external Compose and environment inputs are intentionally absent

The real deployment belongs in LabStack private deployment configuration, not Onebox corpus data.

Verification

• regenerated internal/app/testdata/contract-verdicts.json through TestContractDidNotMove
• go test ./... — 1,530 tests passed across 19 packages
• git diff --check