fix(dagger): stop caching attestation functions across runs
The Dagger module relied on Dagger's default function caching, which keeps a function's result for up to seven days across runs. Attestation functions have side effects and depend on live state, so replaying a cached result causes problems: running init again with the same inputs returns the attestation ID created by an earlier run, and adding evidence to it fails with attestation not yet initialized once that attestation has been pushed. A run identical to a previous one can also be served entirely from the cache and never push an attestation.
This removes that cross-run caching from Init, AddRawEvidence, AddFileEvidence, Push, Status, MarkFailed, MarkCanceled, WorkflowCreate, Container and Debug. They are now cached only for the current session, so every run initializes and pushes its own attestation, while an attestation keeps a single ID for the whole session it was created in. Disabling the cache entirely is not an option, because it would re-initialize the attestation every time it is referenced.
AI assistance: written with Claude Code.