fix(test): self-register Tests\ autoload and migrations dir in bootstrap

The harness failed under a real phpunit run because nothing mapped
Tests\ -> tests/ and Commands\Migration needs migrations/ to exist.
Declare commands:migration as the actual dependency.

packages/test/duckbrain.json

@@ -2,15 +2,25 @@
   "name": "test",
   "version": "0.1.0",
   "description": "Kit de pruebas PHPUnit para Duckbrain",
-  "core": { "requires": ">=0.1", "tested": "0.1" },
+  "core": {
+    "requires": ">=0.1",
+    "tested": "0.1"
+  },
   "php": ">=8.1",
   "components": {
     "harness": {
-      "files": ["phpunit.xml", "tests"],
-      "require": { "commands:cli": ">=0.1" }
+      "files": [
+        "phpunit.xml",
+        "tests"
+      ],
+      "require": {
+        "commands:migration": ">=0.1"
+      }
     }
   },
-  "default": ["harness"],
+  "default": [
+    "harness"
+  ],
   "post-install": [
     "composer require --dev phpunit/phpunit:^11.0 fakerphp/faker",
     "composer dump-autoload"