Incorporate art-dag-mono repo into artdag/ subfolder

Merges full history from art-dag/mono.git into the monorepo
under the artdag/ directory. Contains: core (DAG engine),
l1 (Celery rendering server), l2 (ActivityPub registry),
common (shared templates/middleware), client (CLI), test (e2e).

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

git-subtree-dir: artdag
git-subtree-mainline: 1a179de547
git-subtree-split: 4c2e716558

artdag/l1/pyproject.toml

@@ -0,0 +1,51 @@
+[project]
+name = "art-celery"
+version = "0.1.0"
+description = "Art DAG L1 Server and Celery Workers"
+requires-python = ">=3.11"
+
+[tool.mypy]
+python_version = "3.11"
+warn_return_any = true
+warn_unused_ignores = true
+disallow_untyped_defs = true
+disallow_incomplete_defs = true
+check_untyped_defs = true
+strict_optional = true
+no_implicit_optional = true
+
+# Start strict on new code, gradually enable for existing
+files = [
+    "app/types.py",
+    "app/routers/recipes.py",
+    "tests/",
+]
+
+# Ignore missing imports for third-party packages without stubs
+[[tool.mypy.overrides]]
+module = [
+    "celery.*",
+    "redis.*",
+    "artdag.*",
+    "artdag_common.*",
+    "ipfs_client.*",
+]
+ignore_missing_imports = true
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+python_files = ["test_*.py"]
+python_functions = ["test_*"]
+asyncio_mode = "auto"
+addopts = "-v --tb=short"
+filterwarnings = [
+    "ignore::DeprecationWarning",
+]
+
+[tool.ruff]
+line-length = 100
+target-version = "py311"
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "UP"]
+ignore = ["E501"]  # Line length handled separately