Update EF migrations docs to lead with Aspire.Hosting.EntityFrameworkCore

[Copilot]

The EF Core migrations guide still centered the manual dotnet ef workflow after 13.3 introduced the AppHost-driven hosting integration. This updates the page so the Aspire.Hosting.EntityFrameworkCore flow is the primary path and keeps manual migrations as a shorter fallback.

• Primary workflow: AppHost-managed migrations

  • Reworks the page to lead with the 13.3 hosting integration and Aspire.Hosting.EntityFrameworkCore package.
  • Shows the AppHost-driven migration path as the recommended approach instead of treating dotnet ef as the main workflow.

• Manual workflow demoted to fallback

  • Preserves the manual dotnet ef guidance for teams not using the hosting integration.
  • Narrows that content to a secondary section so it no longer competes with the recommended path.

• Cross-linking

  • Adds/updates cross-reference to the broader Aspire.Hosting.EntityFrameworkCore documentation work tracked separately so readers can move between the migration guide and package-specific guidance.

• Doc scope

  • Keeps the edit focused to src/frontend/src/content/docs/integrations/databases/efcore/migrations.mdx with no unrelated documentation changes.

Example of the updated recommended flow:

var builder = DistributedApplication.CreateBuilder(args);

var sql = builder.AddSqlServer("sql");
var db = sql.AddDatabase("tickets");

builder.AddEFMigrations<SupportTicketApiDataContext>("migrations")
    .WithReference(db);

builder.AddProject<Projects.SupportTicketApi_Api>("api")
    .WithReference(db);

builder.Build().Run();