fix(sync,list): preserve folder membership and list across namespaces

[acmore]

Summary

• preserve Syncthing peer and mesh receiver folder membership so local sync updates do not break worker mesh propagation
• move remote ignore handling to the Syncthing API and keep long-running sync work off the bootstrap timeout
• make okdev list show the current owner's sessions across all namespaces by default, while --namespace narrows the results

Test Plan

• go test ./internal/cli -run 'TestConfigureSyncthingPeerPreservesMeshReceiverFolderPeers|TestConfigureSyncthingPeerAddsAndUpdatesConfig|TestConfigureSyncthingPeerPrunesStaleManagedPeerDevices|TestConfigureSyncthingMeshHub|TestSyncthingSetIgnoresPostsPatterns|TestSyncthingBootstrapAndRuntimeContexts|TestRunSyncHealthLoop|TestNewListCmd|TestNewStatusCmd' -count=1
• .venv/bin/pre-commit run --all-files --hook-stage manual okdev-gofmt