[LarryHu0217]

Fixes #160665.

When an unresolved lazy import causes annotation evaluation to fall back to a ForwardRef for the entire expression, annotations such as InitVar[A] are currently treated as ordinary dataclass fields. Reuse the existing annotation-prefix resolver for this representation.

This restores argument forwarding to __post_init__ and keeps affected ClassVar annotations out of instance fields. The original Field.type and ordinary deferred fields are preserved.

Adds deterministic circular-import fixtures covering direct, qualified and aliased InitVar, a ClassVar case and an ordinary deferred-field control, plus a Library NEWS entry.

Validation on macOS arm64 using the existing --with-pydebug interpreter built at dc28c3a358221b1e0ae5f926b72e112cbd1d03f7 (CPython 3.16.0a1+dev):

• The original three-module reproducer raises the reported missing-__post_init__-argument error before the fix.
• Against unchanged upstream dataclasses.py, the regression has three InitVar subcase errors and one ClassVar assertion failure; the ordinary deferred-field control passes. All five subcases pass after the fix.
• ./python.exe -B -m test -u cpu --timeout 600 test_dataclasses test_annotationlib test_typing test_lazy_import test_inspect: all five suites succeed; reported run=1,708, skipped=1.
• ./python.exe -B -m test -R 3:3 -m test_lazy_import_forwardref_annotations test_dataclasses: success, with no positive leaks in the three measured repetitions.
• Unmodified Tools/patchcheck/patchcheck.py, scoped ruff check --no-fix --no-cache on the four changed Python files, git diff --cached --check and git diff --check: pass.

Ruff was the existing 0.15.22 binary, with its Python-3.15-support warning retained. The hook pins 0.15.17; the full hook runner was not installed or run. An initial attempt with another installed Ruff 0.14.6 could not parse the repository's Python 3.15 target configuration; the successful check used 0.15.22 without changing that configuration.

The dataclasses source and complete owning test tree, annotationlib source/tests, typing source/tests, inspect source and lazy-import test tree match main checked at 2468c35c3b3375fe0745fa5b5429d47098ebb45e. That main is 28 commits ahead of the validation baseline; the compared test-support change concerns sanitizer configuration detection. Later native changes and the entire CPython test suite were not validated locally. No new native build or dependency installation was performed.

• Issue: Lazy imports break dataclass InitVars in extremely rare scenarios #160665