feat: add HTTP Management API, migrate CLI from Akka ClusterClient to HTTP

Replace the CLI's Akka.NET ClusterClient transport with a simple HTTP client
targeting a new POST /management endpoint on the Central Host. The endpoint
handles Basic Auth, LDAP authentication, role resolution, and ManagementActor
dispatch in a single round-trip — eliminating the CLI's Akka, LDAP, and
Security dependencies.

Also fixes DCL ReSubscribeAll losing subscriptions on repeated reconnect by
deriving the tag list from _subscriptionsByInstance instead of _subscriptionIds.

docker/README.md

@@ -185,11 +185,11 @@ curl -s http://localhost:9002/health/ready | python3 -m json.tool
 
 ### CLI Access
 
-Connect the ScadaLink CLI to the central cluster. With OrbStack, the contact point hostname must match the container's Akka `NodeHostname` config, so use the container name directly (OrbStack resolves container names via DNS):
+The CLI connects to the Central Host's HTTP management API. With the Docker setup, the Central UI (and management API) is available at `http://localhost:9001`:
 
 ```bash
 dotnet run --project src/ScadaLink.CLI -- \
-    --contact-points akka.tcp://scadalink@scadalink-central-a:8081 \
+    --url http://localhost:9001 \
     --username multi-role --password password \
     template list
 ```
@@ -200,19 +200,11 @@ A recommended `~/.scadalink/config.json` for the Docker test environment:
 
 ```json
 {
-  "contactPoints": ["akka.tcp://scadalink@scadalink-central-a:8081"],
-  "ldap": {
-    "server": "localhost",
-    "port": 3893,
-    "useTls": false,
-    "searchBase": "dc=scadalink,dc=local",
-    "serviceAccountDn": "cn=admin,dc=scadalink,dc=local",
-    "serviceAccountPassword": "password"
-  }
+  "managementUrl": "http://localhost:9001"
 }
 ```
 
-With this config file in place, the contact points and LDAP settings are automatic:
+With this config file in place, the URL is automatic:
 
 ```bash
 dotnet run --project src/ScadaLink.CLI -- \