Upgrade Python codebase to use Python 3.12+ type syntax

[yesudeep]

Summary

The Python codebase has compatibility code for Python 3.10/3.11 that can be simplified once Python 3.12+ is the minimum supported version.

Location

• python/dotpromptz/src/dotpromptz/resolvers.py:62: # TODO: Python 3.12+:

Acceptance Criteria

• Track Python 3.12 becoming minimum version
• Update type syntax to use Python 3.12+ features
• Remove compatibility shims