Add grounded unified search answers and live verification

src/AdvisoryAI/StellaOps.AdvisoryAI/UnifiedSearch/UnifiedSearchModels.cs

@@ -69,12 +69,50 @@ public sealed record AmbientContext
     public string? SessionId { get; init; }
 
     public bool ResetSession { get; init; }
+
+    public AmbientAction? LastAction { get; init; }
+}
+
+public sealed record AmbientAction
+{
+    public string Action { get; init; } = string.Empty;
+
+    public string? Source { get; init; }
+
+    public string? QueryHint { get; init; }
+
+    public string? Domain { get; init; }
+
+    public string? EntityKey { get; init; }
+
+    public string? Route { get; init; }
+
+    public DateTimeOffset? OccurredAt { get; init; }
 }
 
 public sealed record SearchSuggestion(string Text, string Reason);
 
 public sealed record SearchRefinement(string Text, string Source);
 
+public sealed record ContextAnswer(
+    string Status,
+    string Code,
+    string Summary,
+    string Reason,
+    string Evidence,
+    IReadOnlyList<ContextAnswerCitation>? Citations = null,
+    IReadOnlyList<ContextAnswerQuestion>? Questions = null);
+
+public sealed record ContextAnswerCitation(
+    string EntityKey,
+    string Title,
+    string Domain,
+    string? Route = null);
+
+public sealed record ContextAnswerQuestion(
+    string Query,
+    string Kind = "follow_up");
+
 public sealed record UnifiedSearchResponse(
     string Query,
     int TopK,
@@ -82,7 +120,8 @@ public sealed record UnifiedSearchResponse(
     SynthesisResult? Synthesis,
     UnifiedSearchDiagnostics Diagnostics,
     IReadOnlyList<SearchSuggestion>? Suggestions = null,
-    IReadOnlyList<SearchRefinement>? Refinements = null);
+    IReadOnlyList<SearchRefinement>? Refinements = null,
+    ContextAnswer? ContextAnswer = null);
 
 public sealed record EntityCard
 {