InstanceActor._tagPathToAttribute was a Dictionary<string,string> — one tag
path mapped to a single attribute. When two attributes reference the same PLC
node (e.g. two composed cooling-tank modules both reading ns=3;s=Tank.Level,
or a pump's TempSensor and AlarmSensor both reading ns=3;s=Sensor.Reading),
SubscribeToDcl's map assignment overwrote, so only the last-registered
attribute ever received values — the rest stayed permanently Uncertain.
The map is now Dictionary<string,List<string>>; HandleTagValueUpdate fans each
update out to every attribute referencing the tag path, and each distinct tag
path is still subscribed only once per connection.
HandleSetStaticAttribute was made fire-and-forget (commit 2951507) — it no
longer replies with SetStaticAttributeResponse — but three InstanceActor
tests still ExpectMsg<SetStaticAttributeResponse> and timed out. Verify the
mutation via the GetAttributeRequest round-trip instead, which the FIFO
mailbox makes a sound sync point. Test intent (in-memory update, SQLite
persistence, serialized ordering) is unchanged.
Attributes bound to data connections now initialize with "Uncertain" quality,
distinguishing "never received a value" from "known good" or "connection lost."
Quality is tracked per attribute and included in GetAttributeResponse.
