Task 8 of the fleet-deployment plan. Adds the tines-bt crate: a real
`Transport` over the `bluer` crate (D-Bus BlueZ).
- `Addr` = peer's advertised `NodeId`, so identity survives BLE
address rotation; advertising payload (flags + 16-bit service UUID +
NodeId in service data) fits legacy 31-byte EIR (`advertise()`).
- `BtTransport` drops any inbound frame whose `from` differs from the
connection's advertised NodeId (protocol violation at the transport;
core never sees a mismatch).
- Connection symmetry: the node with the numerically smaller NodeId is
the BLE central/initiator (`is_central`), independent of which side
opens the radio.
- `mtu()` reports the real L2CAP CoC MTU (falling back to the ATT MTU);
the transport does NOT split frames — core folds summaries/fragments
to `mtu()`.
- Radio I/O sits behind the narrow `Radio` trait (a `poll`-driven event
stream), so the pure logic (payload assembly, mismatch-drop, central
rule) is unit-tested with a mock radio and never needs hardware.
- `BluerRadio` drives the stack on a detached tokio task: powers the
adapter, advertises, monitors for the service UUID, opens an L2CAP
byte pipe, and surfaces inbound bytes tagged with the peer NodeId.
Adds `tests/adv.rs` (8 mock-Radio integration tests covering the 31-byte
limit, NodeId round-trip, MTU clamp, mismatch-drop, per-frame MTU, and
central rule). Added to workspace members; workspace CI (fmt, doc,
test, clippy -D warnings) is green.
kyle