fix(fuse): persist object GC claims in publish journal

[wchwawa]

Summary

• persist the exact object-GC claim version in each asynchronous FUSE publish journal record
• reject zero claim versions when appending or replaying records
• fail closed for legacy journal records that cannot prove their object-reference claim
• reconstruct recovery state with the persisted claim instead of inventing a current token

Stack and scope

Depends on #403 and is intentionally separate from the Workbench restore delivery.

This is a narrow publish-journal correctness PR. It changes five nokv-fuse files only.

It does not add operator rollback, mutation fencing, SubtreeReplaced invalidation, remote watch support, or a general automatic object-GC refresh and re-upload loop. Broader restage policy remains deferred.

Validation

• cargo test -p nokv-fuse: 73 passed
• cargo clippy -p nokv-fuse --all-targets -- -D warnings
• cargo test --workspace --all-targets --no-run
• cargo fmt --all -- --check
• git diff --check

The added deterministic tests cover zero-token rejection, legacy-record fail-closed behavior, and exact claim reconstruction during recovery.