fix: rename ACT from "Compact" to "Context" token, add pyproject.toml and PoC plan

Corrects the ACT acronym expansion to "Agent Context Token" in the
reference implementation. Adds proper pyproject.toml for the act package
and the MCP+LangGraph PoC planning document.

workspace/act/pyproject.toml

@@ -0,0 +1,23 @@
+[build-system]
+requires = ["setuptools>=68.0"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "act"
+version = "0.1.0"
+description = "Agent Context Token (ACT) — JWT-based authorization and execution accountability for AI agents"
+requires-python = ">=3.11"
+dependencies = [
+    "cryptography>=42.0",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=8.0",
+]
+
+[tool.setuptools.packages.find]
+where = ["."]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]