Add call graph fixtures for various languages and scenarios

- Introduced `all-edge-reasons.json` to test edge resolution reasons in .NET.
- Added `all-visibility-levels.json` to validate method visibility levels in .NET.
- Created `dotnet-aspnetcore-minimal.json` for a minimal ASP.NET Core application.
- Included `go-gin-api.json` for a Go Gin API application structure.
- Added `java-spring-boot.json` for the Spring PetClinic application in Java.
- Introduced `legacy-no-schema.json` for legacy application structure without schema.
- Created `node-express-api.json` for an Express.js API application structure.

src/Cli/StellaOps.Cli/Output/CliErrorRenderer.cs

@@ -67,6 +67,11 @@ internal static class CliErrorRenderer
         // Error code
         AnsiConsole.MarkupLine($"[grey]Code:[/] {Markup.Escape(error.Code)}");
 
+        if (TryGetReasonCode(error, out var reasonCode))
+        {
+            AnsiConsole.MarkupLine($"[grey]Reason:[/] {Markup.Escape(reasonCode)}");
+        }
+
         // Detail (if present)
         if (!string.IsNullOrWhiteSpace(error.Detail))
         {
@@ -207,5 +212,41 @@ internal static class CliErrorRenderer
         RenderScopeGuidance(error);
         RenderRateLimitGuidance(error);
         RenderAuthGuidance(error);
+        RenderOfflineKitGuidance(error);
+    }
+
+    private static bool TryGetReasonCode(CliError error, out string reasonCode)
+    {
+        reasonCode = "";
+        if (error.Metadata is null || error.Metadata.Count == 0)
+        {
+            return false;
+        }
+
+        if ((!error.Metadata.TryGetValue("reason_code", out reasonCode) || string.IsNullOrWhiteSpace(reasonCode)) &&
+            (!error.Metadata.TryGetValue("reasonCode", out reasonCode) || string.IsNullOrWhiteSpace(reasonCode)))
+        {
+            return false;
+        }
+
+        reasonCode = OfflineKitReasonCodes.Normalize(reasonCode) ?? "";
+        return reasonCode.Length > 0;
+    }
+
+    private static void RenderOfflineKitGuidance(CliError error)
+    {
+        if (!TryGetReasonCode(error, out var reasonCode))
+        {
+            return;
+        }
+
+        var remediation = OfflineKitReasonCodes.GetRemediation(reasonCode);
+        if (string.IsNullOrWhiteSpace(remediation))
+        {
+            return;
+        }
+
+        AnsiConsole.WriteLine();
+        AnsiConsole.MarkupLine($"[yellow]Remediation:[/] {Markup.Escape(remediation)}");
     }
 }