chore: add .editorconfig and consistent formatting for backend projects

Adds an `.editorconfig` file with C# and project-specific conventions. Applies consistent indentation and formatting across backend handlers, runtime models, and AI services.

apps/backend/Program.cs

@@ -6,13 +6,13 @@ var builder = WebApplication.CreateBuilder(args);
 
 builder.Services.AddCors((options) =>
 {
-  options.AddDefaultPolicy((policy) =>
-  {
-    policy
-      .AllowAnyHeader()
-      .AllowAnyMethod()
-      .AllowAnyOrigin();
-  });
+    options.AddDefaultPolicy((policy) =>
+    {
+        policy
+        .AllowAnyHeader()
+        .AllowAnyMethod()
+        .AllowAnyOrigin();
+    });
 });
 builder.Services.Configure<WorldGenerationOptions>(builder.Configuration.GetSection("WorldGeneration"));
 builder.Services.Configure<OrbitalSimulationOptions>(builder.Configuration.GetSection("OrbitalSimulation"));