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/surrealdb/connection.nim

@@ -0,0 +1,27 @@
+import std/asyncdispatch
+import std/os
+import std/strutils
+import ../../src/allographer/connection
+
+proc envStringDefault(key, defaultValue: string): string =
+  let value = getEnv(key)
+  if value.len == 0:
+    return defaultValue
+  return value
+
+proc envIntDefault(key: string, defaultValue: int): int =
+  let value = getEnv(key)
+  if value.len == 0:
+    return defaultValue
+  return value.parseInt
+
+let
+  database = envStringDefault("DB_DATABASE", "test")
+  user = envStringDefault("DB_USER", "user")
+  password = envStringDefault("DB_PASSWORD", "pass")
+  surrealHost = envStringDefault("SURREAL_HOST", "http://surreal")
+  surrealPort = envIntDefault("SURREAL_PORT", 8000)
+  maxConnections = envIntDefault("DB_MAX_CONNECTION", 5)
+  timeout = envIntDefault("DB_TIMEOUT", 30)
+
+let surreal* = dbOpen(SurrealDB, database, database, user, password, surrealHost, surrealPort, maxConnections, timeout, shouldDisplayLog=true).waitFor()