feat: canonical Nim client refactor with typed rows, pool, and allographer wrapper

- Extract wire protocol into clients/nim/src/baradb/wire.nim
- Add BaraError exception hierarchy
- Refactor BaraClient/SyncClient with typedRows, AsyncLock request queue, timeouts, TLS config
- Add BaraPool and optional HTTP fallback
- Add mock-server wire and pool unit tests
- Bump baradb nimble package to 1.2.0
- Make nim-allographer depend on canonical baradb client
- Use typed rows in allographer toJson
- Deprecate src/barabadb/client/client.nim
- Update docs/en/clients.md and clients/nim/README.md

src/barabadb/client/client.nim

@@ -1,3 +1,4 @@
+{.deprecated: "Use the canonical baradb/client from clients/nim instead.".}
 ## BaraDB Client — Nim client library
 import std/asyncdispatch
 import std/asyncnet