v2.0.0 — Reflect-Aware PostgreSQL Client

upq v2.0.0 — Reflect-Aware PostgreSQL Client

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🚀 Key Features

1. Reflection-Based Mapping

• New APIs: query_reflect<T>(), query_reflect_one<T>(), exec_reflect(),
  select_reflect<T>(), select_one_reflect<T>().
• Automatic aggregate → parameter expansion ($1..$N).
• Automatic row → struct / tuple mapping.
• std::optional<T> ↔ NULL, containers ↔ PostgreSQL arrays.
• Tight integration with ureflect.

2. Documentation

• Added Reflect Integration section in results.md.
• Updated index.md, quickstart.md, pool.md, transaction.md with reflect examples.
• Added new milestone PgReflectSystem to roadmap.md.

3. Internal Refactor

• Unified encoding/decoding for std::vector, std::array, and std::optional.
• constexpr-based dispatch and refined trait detection.
• Preserves zero-copy query pipeline semantics.

4. Backward Compatibility

• Legacy APIs (query_awaitable, query_on, PgTransaction::query) remain untouched.
• Reflect-aware mapping is header-only and opt-in.
• Fully compatible with existing PgPool and PgTransaction workflows.

5. Upcoming Work

• Full column-name-based mapping (completed in this release).
• Binary protocol type conversion via PgTypeRegistry.
• Benchmark and metrics subsystem (planned for 2.1+).