[feat](trx-client): per-rig meter supervisor with auto-reconnect

Adds rig_meters: map of per-rig watch::Sender<Option<MeterUpdate>> to
RigRoutingContext with a lazy rig_meter_rx helper. run_meter_supervisor
polls for known short names and spawns one SubscribeMeter TCP connection
per rig; reconnect loop sets TCP_NODELAY and pushes samples into the
per-rig watch so slow SSE readers automatically skip intermediate frames.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/Cargo.toml

@@ -12,4 +12,5 @@ bytes = "1"
 uuid = { workspace = true }
 serde_json = { workspace = true }
 trx-core = { path = "../../trx-core" }
+trx-protocol = { path = "../../trx-protocol" }
 tokio = { workspace = true, features = ["sync"] }