feat(clients): professional clients with tests, CI/CD, and examples

- Python: pyproject.toml, pytest suite (unit + integration), README, examples
- JavaScript: package.json, TypeScript definitions, node:test suite, README, examples
- Nim: integration tests, examples, README, improved nimble tasks
- Rust: fixed nodelay/localhost IPv6 bug, integration tests, examples, README
- Added GitHub Actions CI for all 4 clients against Docker server
- Added docker-compose.test.yml for local integration testing
- Added .gitignore for each client

clients/python/tests/test_query_builder.py

@@ -0,0 +1,109 @@
+"""
+Unit tests for QueryBuilder — no running server required.
+"""
+
+import pytest
+from baradb import Client, QueryBuilder
+
+
+class TestQueryBuilder:
+    def test_simple_select(self):
+        client = Client()
+        qb = QueryBuilder(client)
+        sql = qb.select("name", "age").from_("users").build()
+        assert sql == "SELECT name, age FROM users"
+
+    def test_select_all(self):
+        client = Client()
+        qb = QueryBuilder(client)
+        sql = qb.from_("users").build()
+        assert sql == "SELECT * FROM users"
+
+    def test_where_single(self):
+        client = Client()
+        qb = QueryBuilder(client)
+        sql = qb.select("name").from_("users").where("age > 18").build()
+        assert sql == "SELECT name FROM users WHERE age > 18"
+
+    def test_where_multiple(self):
+        client = Client()
+        qb = QueryBuilder(client)
+        sql = (
+            qb.select("name")
+            .from_("users")
+            .where("age > 18")
+            .where("active = true")
+            .build()
+        )
+        assert sql == "SELECT name FROM users WHERE age > 18 AND active = true"
+
+    def test_join(self):
+        client = Client()
+        qb = QueryBuilder(client)
+        sql = (
+            qb.select("u.name", "o.total")
+            .from_("users u")
+            .join("orders o", "u.id = o.user_id")
+            .build()
+        )
+        assert "JOIN orders o ON u.id = o.user_id" in sql
+
+    def test_left_join(self):
+        client = Client()
+        qb = QueryBuilder(client)
+        sql = (
+            qb.select("u.name", "o.total")
+            .from_("users u")
+            .left_join("orders o", "u.id = o.user_id")
+            .build()
+        )
+        assert "LEFT JOIN orders o ON u.id = o.user_id" in sql
+
+    def test_group_by_having(self):
+        client = Client()
+        qb = QueryBuilder(client)
+        sql = (
+            qb.select("dept", "count(*)")
+            .from_("employees")
+            .group_by("dept")
+            .having("count(*) > 5")
+            .build()
+        )
+        assert "GROUP BY dept" in sql
+        assert "HAVING count(*) > 5" in sql
+
+    def test_order_by(self):
+        client = Client()
+        qb = QueryBuilder(client)
+        sql = qb.select("name").from_("users").order_by("name", "DESC").build()
+        assert "ORDER BY name DESC" in sql
+
+    def test_limit_offset(self):
+        client = Client()
+        qb = QueryBuilder(client)
+        sql = qb.select("name").from_("users").limit(10).offset(5).build()
+        assert "LIMIT 10" in sql
+        assert "OFFSET 5" in sql
+
+    def test_full_complex_query(self):
+        client = Client()
+        qb = QueryBuilder(client)
+        sql = (
+            qb.select("u.name", "count(*) as cnt")
+            .from_("users u")
+            .left_join("orders o", "u.id = o.user_id")
+            .where("u.age > 18")
+            .group_by("u.name")
+            .having("cnt > 3")
+            .order_by("cnt", "DESC")
+            .limit(50)
+            .build()
+        )
+        assert sql.startswith("SELECT")
+        assert "FROM users u" in sql
+        assert "LEFT JOIN orders o ON u.id = o.user_id" in sql
+        assert "WHERE u.age > 18" in sql
+        assert "GROUP BY u.name" in sql
+        assert "HAVING cnt > 3" in sql
+        assert "ORDER BY cnt DESC" in sql
+        assert "LIMIT 50" in sql