feat(driver): add fetch* method aliases compatibility

[cofin]

Summary

Adds fetch* method aliases to sync and async driver base classes, providing an alternative naming convention for users familiar with asyncpg's API. Both select* (primary) and fetch* (alias) naming conventions are fully supported.

The Problem

Users coming from asyncpg expect methods like fetch(), fetchrow(), and fetchval(). SQLSpec uses select(), select_one(), and select_value() which, while more semantic, can feel unfamiliar to asyncpg users.

The Solution

Add wrapper methods that delegate to the existing select* methods with full type safety through duplicated @overload decorators. Both conventions work identically with zero performance overhead.

Key Features

• 7 new sync methods: fetch(), fetch_one(), fetch_one_or_none(), fetch_value(), fetch_value_or_none(), fetch_to_arrow(), fetch_with_total()
• 7 new async methods: Same methods with async implementations
• Full type safety with duplicated overloads for proper IDE support
• 44 unit tests verifying equivalence and delegation behavior
• Documentation updated in drivers_and_querying.rst