fix(gateway): satisfy mypy on nats/grpc adapters and generated proto code

- nats_consumer/grpc_server: annotate nc/sub/server attrs (were inferred
  as None-only from __init__, breaking on the real assignment later).
- active_read: narrow on 'if names:' instead of the derived 'persisted'
  bool so mypy sees names as non-Optional inside the publish_reading call.
- pyproject: exclude ingestor/proto/ (protoc/grpcio-tools output) from
  mypy's file walk and skip following it as an import - it's generated,
  not hand-maintained, and mypy can't see its runtime-built message classes.

ingestor/adapters/grpc_server.py

@@ -51,7 +51,7 @@ class GrpcServer:
         self.logger = logger
         self.port = port
         self.slot_lookup = slot_lookup
-        self.server = None
+        self.server: grpc.aio.Server | None = None
 
     async def start(self) -> None:
         self.server = grpc.aio.server()

ingestor/adapters/nats_consumer.py

@@ -9,6 +9,8 @@ here. No reconnect logic — nats-py handles reconnection internally.
 import json
 
 import nats
+from nats.aio.client import Client
+from nats.aio.subscription import Subscription
 from sientia_do.observability.logger import Logger
 
 from ingestor.engines.write import WriteEngine
@@ -28,8 +30,8 @@ class NatsWriteConsumer:
         self.logger = logger
         self.subject = subject
         self.queue = queue
-        self.nc = None
-        self.sub = None
+        self.nc: Client | None = None
+        self.sub: Subscription | None = None
 
     async def start(self) -> None:
         self.nc = await nats.connect(servers=self.nats_url)

ingestor/engines/active_read.py

@@ -75,7 +75,7 @@ class ActiveReadEngine(SientiaMonitoring):
         await self._record_read_lag(source_ts, tags)
         source_str = self._format_ts(source_ts)
         persisted = bool(names)
-        if persisted:
+        if names:
             await self.sink.publish_reading(
                 tag=addr, value=value, timestamp=source_str, names=names
             )