Support for `lazy` imports (PEP 810, Python 3.15+)

Python 3.15 introduces PEP 810 - Explicit lazy imports via the new lazy soft keyword:

lazy import json
lazy from pathlib import Path

Currently mypy reports these as syntax errors. Support is needed to:

• Update the parser to recognise lazy import and lazy from ... import statements
• Treat lazy imports the same as regular imports for type checking purposes (as noted in PEP 810 § Typing and tools)

Related:

• astral-sh/ruff#21305 (ruff tracking issue)
• astral-sh/ty#2968 (ty tracking issue)

Start by tracing the parser support for lazy import and lazy from ... import statements, then follow the type-checking path for regular imports. Use PEP 810's “Typing and tools” section as the behavioral reference. Done means both forms are accepted and treated like regular imports for type checking without syntax errors.