[What's New Analysis] Create Aspire 13.x migration guide

Summary

Aspire 13.0 and 13.1 have significant breaking changes that are only documented in what's-new. Need a dedicated migration guide.

Breaking Changes to Document

Package Renames

<!-- Before (9.x) -->
<PackageReference Include="Aspire.Hosting.NodeJs" Version="9.x.x" />

<!-- After (13.0) -->
<PackageReference Include="Aspire.Hosting.JavaScript" Version="13.0.0" />

API Signature Changes

AddNodeApp refactored:

// Before (9.x) - absolute scriptPath with optional workingDirectory
builder.AddNodeApp("frontend", "/absolute/path/to/app.js", 
    workingDirectory: "/absolute/path/to");

// After (13.0) - appDirectory with relative scriptPath
builder.AddNodeApp("frontend", "../frontend", "app.js");

AddNpmApp removed:

// Before (9.x)
builder.AddNpmApp("frontend", "../frontend", scriptName: "dev");

// After (13.0)
builder.AddJavaScriptApp("frontend", "../frontend")
    .WithRunScript("dev");

Lifecycle Hooks → Events

// Before (9.x)
public class MyHook : IDistributedApplicationLifecycleHook { ... }
builder.Services.TryAddLifecycleHook<MyHook>();

// After (13.0)
public class MySubscriber : IDistributedApplicationEventingSubscriber { ... }
builder.Services.TryAddEventingSubscriber<MySubscriber>();

Publishing Callbacks → Pipeline Steps

// Before (9.x)
.WithPublishingCallback(async (context, ct) => { ... });

// After (13.0)
.WithPipelineStepFactory(context => new PipelineStep() { ... });

Connection Property Renames (13.1)

Azure Redis Rename (13.1)

// Before
builder.AddAzureRedisEnterprise("cache");

// After
builder.AddAzureManagedRedis("cache");

Suggested Content

1. Quick migration checklist - package updates, API changes
2. Package rename mapping - old → new
3. API signature changes - with before/after examples
4. Lifecycle hooks migration - step-by-step
5. Publishing callbacks migration - step-by-step
6. Breaking behavior changes - EndpointReference.GetValueAsync now waits

Why It Matters

Users upgrading from 9.x hit compilation errors with no clear guidance. What's-new is comprehensive but not organized as a migration checklist.