improve freezable class

[wakamex]

use Freezable as a class mixin instead of a decorator, allowing static typing of methods without stubbing

[dpaiton]

Can you add a PR description? I'm not sure what the outcome of these changes should be.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 97.36842% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 80.63%. Comparing base (7844425) to head (11dc72e).

Files	Patch %	Lines
src/agent0/core/base/types.py	96.29%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1442 +/- ## ========================================== - Coverage 80.75% 80.63% -0.12% ========================================== Files 104 104 Lines 6473 6441 -32 ========================================== - Hits 5227 5194 -33 - Misses 1246 1247 +1 ``` | [Flag](https://app.codecov.io/gh/delvtech/agent0/pull/1442/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=delvtech) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/delvtech/agent0/pull/1442/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=delvtech) | `80.63% <97.36%> (-0.12%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=delvtech#carryforward-flags-in-the-pull-request-comment) to find out more.

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[wakamex]

no more type stubs necessary!

[wakamex]

forgot you were going to review again @dpaiton even though I just requested a review 15 mins ago. we can revert, or add fixes on top.