Put the entrypoint where every other library keeps it

The Composer `files` entry -- the file that declares this library's global
functions -- sat in a subfolder. Across the set there were three conventions
for the same file: src/Functions.php, src/Utils/Functions.php and
src/Utilities/Functions.php, so the answer to "where do the public functions
live" depended on which repository you had open.

It is src/ now, everywhere. Only the `files` entries moved; a Utils/Runtime
is a namespaced class and stays where PSR-4 expects it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Tk8y5eZa3CHVVSM6nVxsJw

Author: arraypress

composer.json

@@ -19,11 +19,11 @@
       "ArrayPress\\RegisterSettingFields\\": "src/"
     },
     "files": [
-      "src/Utilities/Core.php",
-      "src/Utilities/Email.php",
-      "src/Utilities/License.php",
-      "src/Utilities/Page.php",
-      "src/Utilities/TypeCheck.php"
+      "src/Core.php",
+      "src/Email.php",
+      "src/License.php",
+      "src/Page.php",
+      "src/TypeCheck.php"
     ]
   },
   "config": {