fn read_any_layout(ns: &str) -> Option<MuxBusTokens>Expand description
The tokens stored under ns in either layout (chunked split entries or
the single blob), without migrating or deleting anything. None when
neither layout holds a complete, consistent set or a read fails. Used
only to adopt the host-wide session into a channel namespace.
When both layouts are present, the fresher generation wins, the same
rule muxbus_load_tokens applies: on macOS/Linux muxbus_save writes
only the blob, so split entries left over beside it are older and must
not be adopted over it. A blob without a generation (the legacy Windows
format) ranks oldest, so Windows’ current split layout wins over it.