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/seed-sites.sh

@@ -0,0 +1,62 @@
+#!/bin/bash
+set -euo pipefail
+
+# Seed the three test sites with Akka and gRPC addresses.
+# Run after deploy.sh once the central cluster is healthy.
+#
+# Prerequisites:
+#   - Infrastructure services running (infra/docker-compose up -d)
+#   - Application containers running (docker/deploy.sh)
+#   - Central cluster healthy (curl http://localhost:9000/health/ready)
+#
+# Usage:
+#   docker/seed-sites.sh
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+CLI="dotnet run --project $PROJECT_ROOT/src/ScadaLink.CLI --"
+AUTH="--username multi-role --password password"
+URL="--url http://localhost:9000"
+
+echo "=== Seeding ScadaLink Sites ==="
+
+echo ""
+echo "Creating Site-A (Test Plant A)..."
+$CLI $URL $AUTH site create \
+    --name "Test Plant A" \
+    --identifier "site-a" \
+    --description "Test site A - two-node cluster" \
+    --node-a-address "akka.tcp://scadalink@scadalink-site-a-a:8082" \
+    --node-b-address "akka.tcp://scadalink@scadalink-site-a-b:8082" \
+    --grpc-node-a-address "http://scadalink-site-a-a:8083" \
+    --grpc-node-b-address "http://scadalink-site-a-b:8083" \
+|| echo "  (Site-A may already exist)"
+
+echo ""
+echo "Creating Site-B (Test Plant B)..."
+$CLI $URL $AUTH site create \
+    --name "Test Plant B" \
+    --identifier "site-b" \
+    --description "Test site B - two-node cluster" \
+    --node-a-address "akka.tcp://scadalink@scadalink-site-b-a:8082" \
+    --node-b-address "akka.tcp://scadalink@scadalink-site-b-b:8082" \
+    --grpc-node-a-address "http://scadalink-site-b-a:8083" \
+    --grpc-node-b-address "http://scadalink-site-b-b:8083" \
+|| echo "  (Site-B may already exist)"
+
+echo ""
+echo "Creating Site-C (Test Plant C)..."
+$CLI $URL $AUTH site create \
+    --name "Test Plant C" \
+    --identifier "site-c" \
+    --description "Test site C - two-node cluster" \
+    --node-a-address "akka.tcp://scadalink@scadalink-site-c-a:8082" \
+    --node-b-address "akka.tcp://scadalink@scadalink-site-c-b:8082" \
+    --grpc-node-a-address "http://scadalink-site-c-a:8083" \
+    --grpc-node-b-address "http://scadalink-site-c-b:8083" \
+|| echo "  (Site-C may already exist)"
+
+echo ""
+echo "=== Site seeding complete ==="
+echo ""
+echo "Verify with: $CLI $URL $AUTH site list"