[What's New Analysis] Create persistent containers documentation

Summary

Persistent containers (WithLifetime(ContainerLifetime.Persistent)) were enhanced in Aspire 9.4 but have no standalone documentation.

What's Missing

Core API

var database = builder.AddPostgres("postgres")
    .WithLifetime(ContainerLifetime.Persistent)  // Survives app restarts
    .WithExplicitStart();                         // Manual start control

Key Behaviors (from what's-new 9.4)

• Improved lifecycle coordination between WithExplicitStart and Persistent
• Automatic persistent networking - separate Docker network for persistent containers
• Container delay start - more reliable startup sequencing
• Network isolation - persistent vs session-scoped containers use separate networks

Suggested Content

1. When to use persistent containers - stateful services, databases, long-running processes
2. Lifecycle behavior - what happens on app restart
3. Networking - automatic network creation, isolation from session containers
4. WithExplicitStart interaction - how the two features work together
5. Cleanup - how to remove persistent containers
6. Examples - database development, shared cache across runs

Why It Matters

Users frequently ask about keeping databases running across app restarts. Current behavior is undocumented.