feat: standalone Nim client package (baradb) with nimble + 16 tests

Standalone Nim client ():
- Self-contained: no dependency on BaraDB server code
- Inlined wire protocol with full serialization (int32/64, float64, string, bytes, array, object)
- Async client (connect/close/query/exec/ping)
- Sync wrapper (newSyncClient)
- Fluent QueryBuilder (select/from/where/join/groupBy/having/orderBy/limit)
- Nimble package file for ecosystem (nimble install baradb)
- 16 passing tests covering: QueryBuilder (6), Config (3), Wire protocol (5), Client (2)

Also has Python + JS clients with identical API

clients/nim/baradb.nimble

@@ -0,0 +1,16 @@
+# Package
+
+version       = "0.1.0"
+author        = "BaraDB Team"
+description   = "BaraDB client library for Nim — async binary protocol client"
+license       = "Apache-2.0"
+srcDir        = "src"
+
+# Dependencies — only Nim stdlib, no server code
+requires "nim >= 2.2.0"
+
+# Export the client module
+bin           = @[]
+
+task test, "Run client tests":
+  exec "nim c -r tests/test_client.nim"