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/QuietHoursContracts.cs

@@ -0,0 +1,60 @@
+using System.Collections.Immutable;
+
+namespace StellaOps.Notify.WebService.Contracts;
+
+/// <summary>
+/// Request to create or update a quiet hours schedule.
+/// </summary>
+public sealed class QuietHoursUpsertRequest
+{
+    public required string Name { get; init; }
+    public required string CronExpression { get; init; }
+    public required TimeSpan Duration { get; init; }
+    public required string TimeZone { get; init; }
+    public string? ChannelId { get; init; }
+    public bool? Enabled { get; init; }
+    public string? Description { get; init; }
+    public ImmutableDictionary<string, string>? Metadata { get; init; }
+}
+
+/// <summary>
+/// Request to create or update a maintenance window.
+/// </summary>
+public sealed class MaintenanceWindowUpsertRequest
+{
+    public required string Name { get; init; }
+    public required DateTimeOffset StartsAt { get; init; }
+    public required DateTimeOffset EndsAt { get; init; }
+    public bool? SuppressNotifications { get; init; }
+    public string? Reason { get; init; }
+    public ImmutableArray<string> ChannelIds { get; init; } = [];
+    public ImmutableArray<string> RuleIds { get; init; } = [];
+    public ImmutableDictionary<string, string>? Metadata { get; init; }
+}
+
+/// <summary>
+/// Request to create or update a throttle configuration.
+/// </summary>
+public sealed class ThrottleConfigUpsertRequest
+{
+    public required string Name { get; init; }
+    public required TimeSpan DefaultWindow { get; init; }
+    public int? MaxNotificationsPerWindow { get; init; }
+    public string? ChannelId { get; init; }
+    public bool? IsDefault { get; init; }
+    public bool? Enabled { get; init; }
+    public string? Description { get; init; }
+    public ImmutableDictionary<string, string>? Metadata { get; init; }
+}
+
+/// <summary>
+/// Request to create an operator override.
+/// </summary>
+public sealed class OperatorOverrideCreateRequest
+{
+    public required string OverrideType { get; init; }
+    public required DateTimeOffset ExpiresAt { get; init; }
+    public string? ChannelId { get; init; }
+    public string? RuleId { get; init; }
+    public string? Reason { get; init; }
+}