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/tests/baradb/test_query.nim

@@ -0,0 +1,82 @@
+discard """
+  cmd: "nim c -r $file"
+"""
+
+import std/unittest
+import std/asyncdispatch
+import std/json
+import std/options
+import std/strformat
+import ../../src/allographer/query_builder
+import ./connections
+
+
+let rdb = baradb
+
+suite("Baradb query"):
+  test("create table raw"):
+    let sql = """
+      CREATE TABLE IF NOT EXISTS "users" (
+        "id" SERIAL PRIMARY KEY,
+        "name" VARCHAR(255),
+        "email" VARCHAR(255),
+        "age" INTEGER
+      )
+    """
+    waitFor rdb.raw(sql).exec()
+    check true
+
+  test("insert"):
+    waitFor rdb.table("users").insert(%*{ "name": "Alice", "email": "alice@example.com", "age": 30 })
+    waitFor rdb.table("users").insert(%*{ "name": "Bob", "email": "bob@example.com", "age": 25 })
+    check true
+
+  test("get"):
+    let users = waitFor rdb.select("id", "name", "email", "age").table("users").orderBy("id", Asc).get()
+    check users.len >= 2
+    check users[0]["name"].getStr == "Alice"
+    check users[0]["email"].getStr == "alice@example.com"
+    check users[0]["age"].getInt == 30
+
+  test("first"):
+    let user = waitFor rdb.table("users").where("name", "=", "Alice").first()
+    check user.isSome
+    check user.get["name"].getStr == "Alice"
+
+  test("find"):
+    let user = waitFor rdb.table("users").find(1)
+    check user.isSome
+    check user.get["id"].getInt == 1
+
+  test("update"):
+    waitFor rdb.table("users").where("name", "=", "Alice").update(%*{ "age": 31 })
+    let user = waitFor rdb.table("users").where("name", "=", "Alice").first()
+    check user.isSome
+    check user.get["age"].getInt == 31
+
+  test("delete"):
+    waitFor rdb.table("users").where("name", "=", "Bob").delete()
+    let user = waitFor rdb.table("users").where("name", "=", "Bob").first()
+    check user.isNone
+
+  test("count"):
+    let cnt = waitFor rdb.table("users").count()
+    check cnt >= 1
+
+  test("transaction rollback"):
+    waitFor rdb.begin()
+    waitFor rdb.table("users").insert(%*{ "name": "Charlie", "email": "charlie@example.com", "age": 40 })
+    waitFor rdb.rollback()
+    let user = waitFor rdb.table("users").where("name", "=", "Charlie").first()
+    check user.isNone
+
+  test("transaction commit"):
+    waitFor rdb.begin()
+    waitFor rdb.table("users").insert(%*{ "name": "Dave", "email": "dave@example.com", "age": 50 })
+    waitFor rdb.commit()
+    let user = waitFor rdb.table("users").where("name", "=", "Dave").first()
+    check user.isSome
+
+  test("raw select"):
+    let users = waitFor rdb.raw("SELECT * FROM \"users\" WHERE \"age\" > 20").get()
+    check users.len >= 1