Move onto the 0.3.x line

Errors are answered instead of ending the request, what is sent can be validated, and there
is a command line. A response may now carry any status, a request matching no route answers
404 rather than 200, and the container reads a parameter type only when it names one class,
so the stack takes a coordinated step together and asks for `^0.3` of its own packages.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ARqBYLxrHqevcVmxHkpJcZ

Author: Radoslaw Ziemniewicz

composer.json

@@ -32,11 +32,11 @@
     },
     "require-dev": {
         "phpstan/phpstan": "^2.0",
-        "quillstack/unit-tests": "^0.5"
+        "quillstack/unit-tests": "^0.6"
     },
     "extra": {
         "branch-alias": {
-            "dev-main": "0.2.x-dev"
+            "dev-main": "0.3.x-dev"
         }
     },
     "scripts": {