Each subtest now inserts its own PENDING run and runs under
t.Parallel(); shared state across subtests was the only reason they
had to stay sequential. Also adds a round-trip test that exercises
the approval-state fields (PendingToolCalls, PendingApprovals,
ApprovalInput, AllToolCalls, InnerCheckpoints, CompletedCalls) to
catch regressions where Save/Load drops nested or approval payloads.
The nonexistent-run case now uses a valid GID in the same tenant so
it reaches the row-not-found branch instead of short-circuiting on
the tenant-scope guard.
Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>
