build: Add composer setup with phpunit and faker

composer.json

@@ -0,0 +1,15 @@
+{
+    "name": "kj/duckbrain",
+    "description": "DuckBrain microframework - development harness (tests and tooling; never published to master).",
+    "type": "project",
+    "license": "MIT",
+    "require-dev": {
+        "fakerphp/faker": "^1.24",
+        "phpunit/phpunit": "^11.0"
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "Tests\\": "tests/"
+        }
+    }
+}