The 1.0 Python mux, mirroring the Rust donglora-mux 1.0 one-for-one and implementing the full §13 multi-client semantics on the DongLoRa Protocol v2 wire format.
* Structural rewrite. donglora_mux/{daemon,intercept,session,tagmap}.py replace the 601-line __init__.py monolith.
* Tag-aware dispatch. TagMapper with skip-zero allocation and per-client bulk drop on disconnect. Multiple clients can have commands in flight concurrently; the single-oneshot response slot is gone.
* Full §13.2 multi-client SET_CONFIG semantics. Tracks (client_id, modulation) lock owner and synthesizes OK(APPLIED/MINE), OK(ALREADY_MATCHED/OTHER), or OK(LOCKED_MISMATCH/OTHER).
* TX loopback fan-out (§13.4). On TX_DONE(TRANSMITTED) the mux synthesizes an RX frame with origin = LOCAL_LOOPBACK for every connected client except the transmitter.
* Async ERR(EFRAME) fan-out: tag-0 framing errors are broadcast to all clients.
* Per-client TX cache on ClientSession so the loopback fan-out does not need the sender to re-buffer.
* Socket and serial fcntl.flock to prevent multiple mux instances from fighting over the same dongle or socket path.
* 500 ms keepalive matching PROTOCOL.md §3.4 (2x margin on the 1 s inactivity timer), replacing the 5 s cadence from 0.x.
* Clean SIGINT / SIGTERM shutdown: per-client handler tasks are tracked and cancelled, so blocked reader.read() calls no longer pin the event loop open.
