ci: add README.md for coordinode-embedded (maturin requires it)

Author: polaz

coordinode-embedded/README.md

@@ -0,0 +1,42 @@
+# coordinode-embedded
+
+In-process CoordiNode graph database for Python — no server, no Docker required.
+
+```python
+from coordinode_embedded import LocalClient
+
+with LocalClient(":memory:") as db:
+    db.cypher("CREATE (n:Person {name: $name})", {"name": "Alice"})
+    rows = db.cypher("MATCH (n:Person) RETURN n.name AS name")
+    print(rows)  # [{"name": "Alice"}]
+```
+
+## Installation
+
+```bash
+pip install coordinode-embedded
+```
+
+## Usage
+
+`LocalClient` is a drop-in replacement for `CoordinodeClient` for local development,
+notebooks (Jupyter, Google Colab), and testing — same `.cypher()` API, zero infrastructure.
+
+```python
+from coordinode_embedded import LocalClient
+
+# In-memory (discarded on close)
+with LocalClient(":memory:") as db:
+    db.cypher("CREATE (n:Person {name: 'Alice'})")
+    rows = db.cypher("MATCH (n:Person) RETURN n.name AS name")
+
+# Persistent storage
+db = LocalClient("/path/to/db")
+db.cypher("CREATE (n:Item {id: 1})")
+db.close()
+```
+
+## Links
+
+- [CoordiNode](https://github.com/structured-world/coordinode) — the graph database engine
+- [coordinode-python](https://github.com/structured-world/coordinode-python) — Python SDK