Defines `SyncBackend` and `AsyncBackend` protobuf-like protocols using type annotations. This clean interface separates transport logic from client logic, making it trivial to add new backends (e.g., gRPC, custom HTTP) without modifying the client API. It is self-contained and could be extracted as a reusable pattern for any database driver.

Implements `AsyncSyncQueue` that bridges an async producer to a sync consumer (and reverse) with bounded queues and shutdown support. Includes `sync_q` and `async_q` properties for clean backpressure. This is a reusable cross-thread/coroutine communication primitive that can be extracted and used in any mixed-sync/async streaming application.

Provides timezone resolution utilities: `normalize_timezone`, `is_utc_or_fixed`, `utcfromtimestamp` (with epoch arithmetic), and `safe_tzinfo`. These handle DST, Etc/UTC quirks, and PEP 495 fold-ambiguity. The module is dependency-free (uses stdlib `zoneinfo`/`pytz`) and is reusable by any Python project needing robust timezone handling.

Contains reusable custom SQLAlchemy clause elements: `ArrayJoin`, `ClickHouseJoin`, `Lambda`, `PreWhereClause`, `LimitByClause`, and `_JSONSubcolumn`. Each is a self-contained `ClauseElement` subclass with proper `cache_key` support for SQLAlchemy 2.0. These demonstrate how to extend SQLAlchemy's expression language for a specific database and can be adapted for other dialects.

Implements `AsyncSyncQueue`-based streaming classes: `StreamingResponseSource`, `ReadAheadSource`, and `StreamingInsertSource`. These convert async generators into sync iterators (and vice versa) with bounded queues and thread-backed read-ahead. The pattern is transport-agnostic and can be reused in any data pipeline that needs to bridge asyncio and threading contexts.