refactor(notify): merge Notifier WebService into Notify WebService

- Delete dead Notify Worker (NoOp handler)
- Move 51 source files (endpoints, contracts, services, compat stores)
- Transform namespaces from Notifier.WebService to Notify.WebService
- Update DI registrations, WebSocket support, v2 endpoint mapping
- Comment out notifier-web in compose, update gateway routes
- Update architecture docs, port registry, rollout matrix
- Notifier Worker stays as separate delivery engine container

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/Notify/StellaOps.Notify.WebService/Contracts/RiskEventRequest.cs

@@ -0,0 +1,24 @@
+using System.Collections.Generic;
+using System.Text.Json.Nodes;
+
+namespace StellaOps.Notify.WebService.Contracts;
+
+public sealed record RiskEventRequest
+{
+    public Guid EventId { get; init; }
+
+    /// <summary>
+    /// risk.profile.severity.changed | risk.profile.published | risk.profile.deprecated | risk.profile.thresholds.changed
+    /// </summary>
+    public string? Kind { get; init; }
+
+    public string? Actor { get; init; }
+
+    public DateTimeOffset? Timestamp { get; init; }
+
+    public JsonObject? Payload { get; init; }
+
+    public IDictionary<string, string>? Attributes { get; init; }
+
+    public string? ResumeToken { get; init; }
+}