Add Rider launch profiles, fix DI and migrations for dev startup

- Rider launch profiles: "ScadaLink Central" and "ScadaLink Site"
- appsettings.Central.json: correct test_infra credentials (ScadaLink_Dev1#,
  scadalink_app user, GLAuth on 3893, Mailpit on 1025)
- Fix HealthMonitoring DI: split site vs central registration to avoid
  missing IHealthReportTransport on central
- Regenerate single clean EF migration (InitialSchema) covering all entities
- Suppress PendingModelChangesWarning in dev mode
- Fix isDevelopment check for ASPNETCORE_ENVIRONMENT propagation

Verified: Host starts, connects to SQL Server, applies migrations, boots
Akka.NET cluster, LDAP auth works (admin/password via GLAuth), health
endpoint returns Healthy.

src/ScadaLink.Host/appsettings.Central.json

@@ -2,13 +2,13 @@
   "ScadaLink": {
     "Node": {
       "Role": "Central",
-      "NodeHostname": "central-node1",
+      "NodeHostname": "localhost",
       "RemotingPort": 8081
     },
     "Cluster": {
       "SeedNodes": [
-        "akka.tcp://scadalink@central-node1:8081",
-        "akka.tcp://scadalink@central-node2:8081"
+        "akka.tcp://scadalink@localhost:8081",
+        "akka.tcp://scadalink@localhost:8082"
       ],
       "SplitBrainResolverStrategy": "keep-oldest",
       "StableAfter": "00:00:15",
@@ -17,8 +17,8 @@
       "MinNrOfMembers": 1
     },
     "Database": {
-      "ConfigurationDb": "Server=localhost,1433;Database=ScadaLink_Config;User Id=sa;Password=YourPassword;TrustServerCertificate=True",
-      "MachineDataDb": "Server=localhost,1433;Database=ScadaLink_MachineData;User Id=sa;Password=YourPassword;TrustServerCertificate=True"
+      "ConfigurationDb": "Server=localhost,1433;Database=ScadaLinkConfig;User Id=scadalink_app;Password=ScadaLink_Dev1#;TrustServerCertificate=true",
+      "MachineDataDb": "Server=localhost,1433;Database=ScadaLinkMachineData;User Id=scadalink_app;Password=ScadaLink_Dev1#;TrustServerCertificate=true"
     },
     "Security": {
       "LdapServer": "localhost",
@@ -26,7 +26,7 @@
       "LdapUseTls": false,
       "AllowInsecureLdap": true,
       "LdapSearchBase": "dc=scadalink,dc=local",
-      "JwtSigningKey": "CHANGE-ME-development-signing-key-at-least-32-chars",
+      "JwtSigningKey": "scadalink-dev-jwt-signing-key-must-be-at-least-32-characters-long",
       "JwtExpiryMinutes": 15,
       "IdleTimeoutMinutes": 30
     },
@@ -44,7 +44,12 @@
     "InboundApi": {
       "DefaultMethodTimeout": "00:00:30"
     },
-    "Notification": {},
+    "Notification": {
+      "SmtpServer": "localhost",
+      "SmtpPort": 1025,
+      "AuthMode": "None",
+      "FromAddress": "scada-notifications@company.com"
+    },
     "Logging": {
       "MinimumLevel": "Information"
     }