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/act/__init__.py

@@ -1,4 +1,4 @@
-"""Agent Compact Token (ACT) — Reference Implementation.
+"""Agent Context Token (ACT) — Reference Implementation.
 
 A JWT-based format for autonomous AI agents that unifies authorization
 and execution accountability in a single token lifecycle.

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"]