feat(clients): add nim-allographer client with BaraDB driver support

- Pure Nim wire protocol client (async + sync, no C FFI)
- Query Builder: fluent API, SQL generator, execution, transactions
- Schema Builder: create/alter/drop tables, column operations
- Connection pool with aging and timeout handling
- ORM integration via compile-time DB_BARADB switch
- Tests: test_open, test_query
- Documentation: README.md, PLAN_BARADB.md

clients/nim-allographer/compose.test.yaml

@@ -0,0 +1,50 @@
+services:
+  app:
+    build:
+      context: .
+      dockerfile: ./docker/ubuntu/test.Dockerfile
+      args:
+        NIM_VERSION: "${NIM_VERSION:-2.2.8}"
+    tty: true
+    volumes:
+      - .:/root/project
+    depends_on:
+      - postgres
+      - mysql
+      - mariadb
+      - surreal
+
+  mysql:
+    image: mysql:8.0-debian
+    tty: true
+    environment:
+      MYSQL_ROOT_PASSWORD: root
+      MYSQL_DATABASE: database
+      MYSQL_USER: user
+      MYSQL_PASSWORD: pass
+
+  mariadb:
+    image: mariadb
+    tty: true
+    command: --default-authentication-plugin=mysql_native_password
+    environment:
+      MYSQL_ROOT_PASSWORD: root
+      MYSQL_DATABASE: database
+      MYSQL_USER: user
+      MYSQL_PASSWORD: pass
+
+  postgres:
+    image: postgres:alpine
+    tty: true
+    environment:
+      POSTGRES_DB: database
+      POSTGRES_USER: user
+      POSTGRES_PASSWORD: pass
+
+  surreal:
+    image: surrealdb/surrealdb:v3.0
+    tty: true
+    # command: start --log trace --user user --pass pass memory # like redis
+    # command: start --log trace --user user --pass pass file://root/.surrealdb # like mongo
+    command: start --log trace --user user --pass pass memory # like in-memory sqlite
+    # command: start --log trace --user user --pass pass file://root/.surrealdb # like rdb