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/example/run.nim

@@ -0,0 +1,131 @@
+import strformat, json, asyncdispatch
+
+import ../src/allographer/query_builder
+import ../src/allographer/schema_builder
+
+from connections import rdb
+
+rdb.create([
+  table("auth",[
+    Column.increments("id"),
+    Column.string("auth")
+  ]),
+  table("users",[
+    Column.increments("id"),
+    Column.string("name").nullable(),
+    Column.string("email").nullable(),
+    Column.string("password").nullable(),
+    Column.string("address").nullable(),
+    Column.date("birth_date").nullable(),
+    Column.foreign("auth_id").reference("id").onTable("auth").onDelete(SET_NULL)
+  ])
+])
+
+# シーダー
+seeder rdb, "auth":
+  rdb.table("auth").insert(@[
+    %*{"auth": "admin"},
+    %*{"auth": "user"}
+  ])
+  .waitFor()
+
+seeder rdb, "users":
+  let total = 20
+  var insertData: seq[JsonNode]
+  for i in 1..total:
+    let authId = if i mod 2 == 0: 1 else: 2
+    insertData.add(
+      %*{
+        "name": &"user{i}",
+        "email": &"user{i}@gmail.com",
+        "password": &"password{i}",
+        "auth_id": authId
+      }
+    )
+
+  rdb.table("users").insert(insertData).waitFor()
+
+  echo rdb.table("users").get().waitFor()
+
+echo rdb
+    .select("users.id", "users.email")
+    .table("users")
+    .where("name", "=", "user3")
+    .orWhere("name", "=", "user4")
+    .orWhere("users.id", "=", 5)
+    .join("auth", "auth.id", "=", "users.auth_id")
+    .limit(10)
+    .get()
+    .waitFor()
+
+echo rdb.select("id", "email").table("users").limit(5).get().waitFor()
+echo rdb.select("id", "email").table("users").limit(5).first().waitFor()
+echo rdb.table("users").find(4).waitFor()
+echo rdb.select("id", "email").table("users").limit(5).find(3).waitFor()
+
+echo ""
+
+rdb.table("users").insert(%*{"name": "John", "email": "John@gmail.com"}).waitFor()
+echo rdb.table("users").insertId(%*{"name": "John", "email": "John@gmail.com"}).waitFor()
+
+
+rdb.table("users").insert(
+  @[
+      %*{"name": "John", "email": "John@gmail.com"},
+      %*{"name": "Paul", "email": "Paul@gmail.com"}
+  ]
+)
+.waitFor()
+
+rdb.table("users").insert(
+  @[
+      %*{"name": "Mick", "email": "Mick@gmail.com"},
+      %*{"name": "Keith", "password": "KeithPass"}
+  ]
+)
+.waitFor()
+
+
+rdb.table("users").where("id", "=", 2).update(%*{"name": "David"}).waitFor()
+rdb.table("users").where("id", "=", 2).update(%*{"name": "David"}).waitFor()
+echo rdb.select().table("users").where("name", "=", "David").get().waitFor()
+echo rdb.table("users").find(2).waitFor()
+
+rdb.table("users").where("name", "=", "David").delete().waitFor()
+rdb.table("users").delete(3).waitFor()
+echo rdb.table("users").find(3).waitFor()
+echo rdb.table("users").limit(5).get().waitFor()
+echo rdb.select("name").table("users").where("address", "is", nil).get().waitFor()
+
+# sql check
+let r = rdb
+    .select("users.id", "users.email")
+    .table("users")
+    .where("name", "=", "user3")
+    .where("name", "=", "user4")
+    .where("users.id", "=", 5)
+    .orWhere("name", "=", "user6")
+    .orWhere("users.id", "=", 7)
+    .join("auth", "auth.id", "=", "users.auth_id")
+    .limit(10)
+    .get()
+    .waitFor()
+echo r[0]["id"]
+echo r[0]["id"].type
+echo r[0]["email"]
+echo r[0]["email"].type
+
+type User = ref object
+  id:int
+  name:string
+  email:string
+  password:string
+  address:string
+  birth_date:string
+  auth_id:int
+let users = rdb.table("users").limit(5).get().orm(User).waitFor()
+for user in users:
+  echo user.name
+
+waitFor rdb.raw("DROP TABLE users").exec()
+waitFor rdb.raw("DROP TABLE auth").exec()