feat: complete gRPC streaming channel — site host, docker config, docs, integration tests

Switch site host to WebApplicationBuilder with Kestrel HTTP/2 gRPC server,
add GrpcPort/keepalive config, wire SiteStreamManager as ISiteStreamSubscriber,
expose gRPC ports in docker-compose, add site seed script, update all 10
requirement docs + CLAUDE.md + README.md for the new dual-transport architecture.

docker/docker-compose.yml

@@ -40,6 +40,7 @@ services:
       SCADALINK_CONFIG: Site
     ports:
       - "9021:8082"   # Akka remoting (host access for debugging)
+      - "9023:8083"   # gRPC streaming
     volumes:
       - ./site-a-node-a/appsettings.Site.json:/app/appsettings.Site.json:ro
       - ./site-a-node-a/data:/app/data
@@ -55,6 +56,7 @@ services:
       SCADALINK_CONFIG: Site
     ports:
       - "9022:8082"   # Akka remoting
+      - "9024:8083"   # gRPC streaming
     volumes:
       - ./site-a-node-b/appsettings.Site.json:/app/appsettings.Site.json:ro
       - ./site-a-node-b/data:/app/data
@@ -70,6 +72,7 @@ services:
       SCADALINK_CONFIG: Site
     ports:
       - "9031:8082"   # Akka remoting
+      - "9033:8083"   # gRPC streaming
     volumes:
       - ./site-b-node-a/appsettings.Site.json:/app/appsettings.Site.json:ro
       - ./site-b-node-a/data:/app/data
@@ -85,6 +88,7 @@ services:
       SCADALINK_CONFIG: Site
     ports:
       - "9032:8082"   # Akka remoting
+      - "9034:8083"   # gRPC streaming
     volumes:
       - ./site-b-node-b/appsettings.Site.json:/app/appsettings.Site.json:ro
       - ./site-b-node-b/data:/app/data
@@ -100,6 +104,7 @@ services:
       SCADALINK_CONFIG: Site
     ports:
       - "9041:8082"   # Akka remoting
+      - "9043:8083"   # gRPC streaming
     volumes:
       - ./site-c-node-a/appsettings.Site.json:/app/appsettings.Site.json:ro
       - ./site-c-node-a/data:/app/data
@@ -115,6 +120,7 @@ services:
       SCADALINK_CONFIG: Site
     ports:
       - "9042:8082"   # Akka remoting
+      - "9044:8083"   # gRPC streaming
     volumes:
       - ./site-c-node-b/appsettings.Site.json:/app/appsettings.Site.json:ro
       - ./site-c-node-b/data:/app/data