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/mariadb/test_create_schema.nim

@@ -0,0 +1,108 @@
+discard """
+  cmd: "nim c -d:reset $file"
+"""
+
+# nim c -d:reset -r tests/mariadb/test_create_schema.nim
+
+import std/unittest
+import std/asyncdispatch
+import std/os
+import std/strutils
+import std/json
+import ../../src/allographer/schema_builder
+import ./connections
+import ../clear_tables
+
+
+let rdb = mariadb
+let schemaFilePath = getCurrentDir() / "schema.nim"
+clearTables(rdb).waitFor()
+
+suite "Schema output after migration":
+  setup:
+    # schema.nim ファイルの削除
+    if fileExists(schemaFilePath):
+      removeFile(schemaFilePath)
+
+    rdb.create(
+      table("int_relation", [
+        Column.increments("id")
+      ]),
+      table("str_relation", [
+        Column.uuid("uuid")
+      ]),
+      table("test_schema_output", [
+        Column.increments("id"),
+        Column.integer("integer"),
+        Column.smallInteger("smallInteger"),
+        Column.mediumInteger("mediumInteger"),
+        Column.bigInteger("bigInteger"),
+        Column.decimal("decimal", 10, 3),
+        Column.double("double", 10, 3),
+        Column.float("float"),
+        Column.uuid("uuid"),
+        Column.char("char", 255),
+        Column.string("string"),
+        Column.text("text"),
+        Column.mediumText("mediumText"),
+        Column.longText("longText"),
+        Column.date("date"),
+        Column.datetime("datetime"),
+        Column.time("time"),
+        Column.timestamp("timestamp"),
+        Column.timestamps(),
+        Column.softDelete(),
+        Column.binary("binary"),
+        Column.boolean("boolean"),
+        Column.enumField("enumField", ["A", "B", "C"]),
+        Column.json("json"),
+        Column.foreign("int_relation_id").reference("id").onTable("int_relation").onDelete(SET_NULL),
+        Column.strForeign("str_relation_id").reference("uuid").onTable("str_relation").onDelete(SET_NULL)
+      ])
+    )
+
+
+  test "should generate schema.nim file":
+    # スキーマ生成
+    rdb.createSchema(schemaFilePath).waitFor()
+    
+    # schema.nim ファイルの存在確認
+    check fileExists(schemaFilePath)
+    
+    # ファイル内容の検証
+    let schemaContent = readFile(schemaFilePath)
+    echo "schemaContent: ", schemaContent
+    check schemaContent.contains("type TestSchemaOutputTable* = object")
+    check schemaContent.contains("## test_schema_output")
+    check schemaContent.contains("integer*: int")
+    check schemaContent.contains("smallInteger*: int")
+    check schemaContent.contains("mediumInteger*: int")
+    check schemaContent.contains("bigInteger*: int")
+    check schemaContent.contains("decimal*: float")
+    check schemaContent.contains("double*: float")
+    check schemaContent.contains("float*: float")
+    check schemaContent.contains("uuid*: string")
+    check schemaContent.contains("char*: string")
+    check schemaContent.contains("string*: string")
+    check schemaContent.contains("text*: string")
+    check schemaContent.contains("mediumText*: string")
+    check schemaContent.contains("longText*: string")
+    check schemaContent.contains("date*: string")
+    check schemaContent.contains("datetime*: string")
+    check schemaContent.contains("time*: string")
+    check schemaContent.contains("timestamp*: string")
+    check schemaContent.contains("created_at*: string")
+    check schemaContent.contains("updated_at*: string")
+    check schemaContent.contains("deleted_at*: string")
+    check schemaContent.contains("binary*: string")
+    check schemaContent.contains("boolean*: bool")
+    check schemaContent.contains("enumField*: string")
+    check schemaContent.contains("json*: string")
+    check schemaContent.contains("int_relation_id*: int")
+    check schemaContent.contains("str_relation_id*: string")
+
+
+# clearTables(rdb).waitFor()
+# schema.nim ファイルの削除
+if fileExists(schemaFilePath):
+  removeFile(schemaFilePath)