P3 closes the publisher wiring loop. `main.rs` now:
1. builds `PublisherInputs` from CLI args via the pure helper
extracted last iter,
2. opens a `broadcast::channel::<VitalsSnapshot>(256)`,
3. calls `runtime::spawn_publisher(inputs, rx)` — a thin
wrapper around ADR-115's `publisher::spawn` that owns the
`Arc<MqttConfig>` wrap,
4. holds the tx side so the channel stays open until P3.5
wires the sensing-server bridge,
5. awaits Ctrl-C or unexpected publisher exit (logged at WARN).
Two new tests:
* `spawn_publisher_returns_live_handle_without_broker` — proves
the wiring compiles and the rumqttc event loop survives an
unreachable broker (it retries internally; we abort the handle
inside 100 ms). Catches breakage from a future refactor that
accidentally pre-validates host reachability.
* `default_state_channel_capacity_is_reasonable` — locks the
`DEFAULT_STATE_CHANNEL_CAPACITY = 256` default; a regression to
e.g. 1 would surface here instead of as a dropped frame in
production under bursty multi-Seed federation.
12/12 cog-ha-matter tests green (10 → 12).
ADR-116 phase table: P3 flipped from "in progress" to ✅ wiring done,
with the P3.5 follow-up (sensing-server `/v1/snapshot` WS bridge)
explicitly named.
Co-Authored-By: claude-flow <ruv@ruv.net>
c9f005c360