Fix day count schema: allow 2-7 days instead of hardcoded 3

The [Length(3,3)] attribute on Itinerary.Days forced exactly 3 days
regardless of user selection (2-7). Changed to [Length(1,7)] to match
the UI range.

Author: mattleibow

10.0/AI/LocalChatClientWithAgents/src/Models/Itinerary.cs

@@ -17,8 +17,8 @@ public record Itinerary
 	[Description("An explanation of how the itinerary meets the person's special requests.")]
 	public required string Rationale { get; init; }
 
-	[Description("A list of day-by-day plans.")]
-	[Length(3, 3)]
+	[Description("A list of day-by-day plans matching the requested number of days.")]
+	[Length(2, 7)]
 	public required List<DayPlan> Days { get; init; }
 
 	public static Itinerary GetExampleTripToJapan() =>

10.0/AI/LocalChatClientWithAgents/src/ViewModels/TripPlanningViewModel.cs

@@ -35,7 +35,7 @@ public partial class TripPlanningViewModel(TaggingService taggingService) : Obse
 	void DecrementDays() => DayCount--;
 
 	bool CanIncrementDays() => DayCount < 7;
-	bool CanDecrementDays() => DayCount > 1;
+	bool CanDecrementDays() => DayCount > 2;
 
 	public async Task InitializeAsync()
 	{