Add project scaffold: contracts, schemas, docker-compose, workplans

Phase 0 contracts (event envelope, ActivityDefinition, idempotency doc,
naming conventions) and Phase 1 Temporal cluster setup (docker-compose.dev.yml,
Temporal dynamic config) are complete. Includes Pydantic models, JSON schemas,
wiki architecture docs, and ADR-001 workplan files for both workstreams.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -0,0 +1,30 @@
+[project]
+name = "activity-core"
+version = "0.1.0"
+requires-python = ">=3.11"
+dependencies = [
+    "pydantic>=2.0",
+    "temporalio>=1.7",
+    "asyncpg>=0.29",
+    "sqlalchemy[asyncio]>=2.0",
+    "fastapi>=0.115",
+    "uvicorn[standard]>=0.32",
+    "alembic>=1.14",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=8.0",
+    "pytest-asyncio>=0.24",
+    "temporalio[testing]>=1.7",
+]
+
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/activity_core"]