chore(config): update pyproject.toml with project description and requirements

- Add [tool.poetry] section with package-mode=false.
- Update project description.
- Change requires-python from "^3.14" to ">=3.11".
- Minor formatting in authors.

pyproject.toml

@@ -1,11 +1,14 @@
+[tool.poetry]
+package-mode = false
+
 [project]
 name = "nerdletter"
 version = "0.1.0"
-description = ""
+description = "A simple tool for encrypting/decrypting messages using a one-time pad."
 authors = [
-    {name = "Gregory Gauthier",email = "gregory.gauthier@perspectum.com"}
+    {name = "Gregory Gauthier", email = "gregory.gauthier@perspectum.com"}
 ]
-requires-python = "^3.14"
+requires-python = ">=3.11"
 dependencies = [
 ]