TestBundleImport_ValidJSON passed nil broadcaster to BundleHandler.
bundle.Import calls broadcaster.RecordAndBroadcast unconditionally → panic
when broadcaster is nil.
Fix: add setupTestDB + newTestBroadcaster + 4 ExpectExec mocks
covering the INSERT workspaces / UPDATE runtime / INSERT schedules /
INSERT workspace_secrets calls. Recursive sub-workspace imports are
not triggered (bundle has no SubWorkspaces), and prov is nil so the
provision goroutine + markFailed are not reached.
Also caught: the original test never called setupTestDB, so db.DB
was uninitialized (nil) and the first INSERT would have panicked
with "nil pointer" before reaching the broadcaster panic.
