Add Vexer connector suite, format normalizers, and tooling

src/StellaOps.Vexer.Connectors.Abstractions/VexConnectorMetadataBuilder.cs

@@ -0,0 +1,37 @@
+using System.Collections.Immutable;
+
+namespace StellaOps.Vexer.Connectors.Abstractions;
+
+/// <summary>
+/// Builds deterministic metadata dictionaries for raw documents and logging scopes.
+/// </summary>
+public sealed class VexConnectorMetadataBuilder
+{
+    private readonly SortedDictionary<string, string> _values = new(StringComparer.Ordinal);
+
+    public VexConnectorMetadataBuilder Add(string key, string? value)
+    {
+        if (!string.IsNullOrWhiteSpace(key) && !string.IsNullOrWhiteSpace(value))
+        {
+            _values[key] = value!;
+        }
+
+        return this;
+    }
+
+    public VexConnectorMetadataBuilder Add(string key, DateTimeOffset value)
+        => Add(key, value.ToUniversalTime().ToString("O"));
+
+    public VexConnectorMetadataBuilder AddRange(IEnumerable<KeyValuePair<string, string?>> items)
+    {
+        foreach (var item in items)
+        {
+            Add(item.Key, item.Value);
+        }
+
+        return this;
+    }
+
+    public ImmutableDictionary<string, string> Build()
+        => _values.ToImmutableDictionary(static pair => pair.Key, static pair => pair.Value, StringComparer.Ordinal);
+}