chore: some minor cleanup

- update readme
- remote references to pylint
- more exceptions to common instead of utils (there are more internal)
- hide legacy 'experimental' stuff under TYPE_CHECKING

core: fix support for annotations defined with python3.12 'type' keyword

general: set min version to 3.12; update ci to run 3.14

It's a bit of a toll to support so many versions, especially with new 3.12 type syntax and other goodies.

With pyenv/uv these days using custom python version is far easier than before and even preferred.

chore: deprecate python 3.9 support, it's EOL soon

tests: mark test_concurrent_writes as flaky on osx

general: switch from deprecated apprdirs to platformdirs, update readme

marshall.cachew: better exception in case we fail to get type hints f…

…rom type

general: add extra tests for new style type annotations

also update readme

ci: update actions versions

fix handling of undefined type annotations when from __future__ impor…

…t annotations is on