fix(host): resolve Host-005..011 — async startup, HOCON escaping, port-conflict check, dead-config cleanup, migration retry, log-level wiring; Host-002 flagged

src/ScadaLink.Host/LoggerConfigurationFactory.cs

@@ -0,0 +1,48 @@
+using Serilog;
+using Serilog.Events;
+
+namespace ScadaLink.Host;
+
+/// <summary>
+/// Builds the Serilog <see cref="LoggerConfiguration"/> for the Host process.
+///
+/// REQ-HOST-8 / Host-011: the configured minimum level comes from
+/// <c>ScadaLink:Logging:MinimumLevel</c> (bound to <see cref="LoggingOptions"/>) so an
+/// operator editing that key changes the effective log level. The standard
+/// <c>Serilog</c> configuration section is still read (via
+/// <see cref="Serilog.Configuration.ConfigurationLoggerConfigurationExtensions"/>)
+/// for sink/override customisation; the explicit <c>MinimumLevel.Is</c> below pins
+/// the floor from <see cref="LoggingOptions"/>.
+/// </summary>
+public static class LoggerConfigurationFactory
+{
+    public static LoggerConfiguration Build(
+        IConfiguration configuration,
+        string nodeRole,
+        string siteId,
+        string nodeHostname)
+    {
+        var loggingOptions = new LoggingOptions();
+        configuration.GetSection("ScadaLink:Logging").Bind(loggingOptions);
+
+        var minimumLevel = ParseLevel(loggingOptions.MinimumLevel);
+
+        return new LoggerConfiguration()
+            .ReadFrom.Configuration(configuration)
+            .MinimumLevel.Is(minimumLevel)
+            .Enrich.WithProperty("SiteId", siteId)
+            .Enrich.WithProperty("NodeHostname", nodeHostname)
+            .Enrich.WithProperty("NodeRole", nodeRole);
+    }
+
+    /// <summary>
+    /// Parses a Serilog <see cref="LogEventLevel"/> name, falling back to
+    /// <see cref="LogEventLevel.Information"/> for null/blank/unrecognised values.
+    /// </summary>
+    private static LogEventLevel ParseLevel(string? level)
+    {
+        return Enum.TryParse<LogEventLevel>(level, ignoreCase: true, out var parsed)
+            ? parsed
+            : LogEventLevel.Information;
+    }
+}