ARCH-2: add Aspire AppHost + ServiceDefaults (Aspire 13.4.2)

- New projects GerbilManager.AppHost / GerbilManager.ServiceDefaults (templates)
- Added both to GerbilManager.slnx
- WebAPI references ServiceDefaults; AddServiceDefaults + MapDefaultEndpoints wired

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

GerbilManager.AppHost/AppHost.cs

@@ -0,0 +1,3 @@
+var builder = DistributedApplication.CreateBuilder(args);
+
+builder.Build().Run();

GerbilManager.AppHost/GerbilManager.AppHost.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Aspire.AppHost.Sdk/13.4.2">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <UserSecretsId>b153f50c-bec1-401e-9893-f9df7cff2ebd</UserSecretsId>
+  </PropertyGroup>
+
+</Project>

GerbilManager.AppHost/Properties/launchSettings.json

@@ -0,0 +1,29 @@
+{
+  "$schema": "https://json.schemastore.org/launchsettings.json",
+  "profiles": {
+    "https": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "https://localhost:17004;http://localhost:15265",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development",
+        "DOTNET_ENVIRONMENT": "Development",
+        "ASPIRE_DASHBOARD_OTLP_ENDPOINT_URL": "https://localhost:21284",
+        "ASPIRE_RESOURCE_SERVICE_ENDPOINT_URL": "https://localhost:22112"
+      }
+    },
+    "http": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": true,
+      "applicationUrl": "http://localhost:15265",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development",
+        "DOTNET_ENVIRONMENT": "Development",
+        "ASPIRE_DASHBOARD_OTLP_ENDPOINT_URL": "http://localhost:19171",
+        "ASPIRE_RESOURCE_SERVICE_ENDPOINT_URL": "http://localhost:20259"
+      }
+    }
+  }
+}

GerbilManager.AppHost/appsettings.Development.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

GerbilManager.AppHost/appsettings.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning",
+      "Aspire.Hosting.Dcp": "Warning"
+    }
+  }
+}

GerbilManager.AppHost/aspire.config.json

@@ -0,0 +1,5 @@
+{
+  "appHost": {
+    "path": "GerbilManager.AppHost.csproj"
+  }
+}