[Rewrite] sqrt(x**2) -> abs(x) (#59)

[ArthurPendragn]

Closes #59

• New ops: SQRT, ABS, SQUARE added to NumericOpType + dispatch
• Constructor refactor: NumericOp now accepts either a func or a type directly, enabling synthetic nodes (e.g. the replacement ABS op)
• x**2 support: BinOp(**2) now canonicalizes to SQUARE, making it rewrite-eligible
• New rewrite pass: eliminate_sqrt_square replaces SQUARE → SQRT chains with ABS
• Config toggle: AlgebraicRewritesConfig.sqrt_square (default on)
• 11 new tests

[e-strauss]

Hi @ArthurPendragn thanks for your first contribution :)

Overall the PR looks good I think, I added some minor comments and please take a look at the failing tests. you can also run the test locally with:

cd stratum
pytest -v tests

You can just add commits to this branch, I will squash them during merge.

[codecov]

Codecov Report

❌ Patch coverage is 93.65079% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
stratum/optimizer/ir/_numeric_ops.py	90.47%	2 Missing and 2 partials ⚠️

Flag	Coverage Δ
unittests	91.59% <93.65%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
stratum/optimizer/_algebraic_rewrites.py	100.00% <100.00%> (ø)
stratum/optimizer/_numeric_rewrites.py	100.00% <100.00%> (ø)
stratum/optimizer/ir/_numeric_ops.py	94.93% <90.47%> (-5.07%)	⬇️

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[e-strauss]

LGTM