add repository scaffolding

Ignore rules, markdown lint configuration and the pointer to AGENTS.md, so the
node itself arrives as a reviewable diff rather than as an initial import.

.gitignore

@@ -0,0 +1,14 @@
+__pycache__/
+*.py[cod]
+*$py.class
+*.egg-info/
+dist/
+build/
+*.egg
+.env
+.venv
+.pytest_cache/
+.coverage
+.ruff_cache/
+out/
+.dora/

.markdownlint.json

@@ -0,0 +1,7 @@
+{
+  "MD013": {
+    "line_length": 120,
+    "tables": false,
+    "code_blocks": false
+  }
+}

CLAUDE.md

@@ -0,0 +1,3 @@
+# CLAUDE.md
+
+See [AGENTS.md](AGENTS.md) for repository guidance.