test: Check hugr json serializations against the schema (again)

[aborgna-q]

Removed in #2186

[acl-cqc]

This feels quite heavyweight for a pre-commit, but I don't really object

[aborgna-q]

This is just the rule ran on just check. pre-commit has its own config that doesn't set the envvar.

[acl-cqc]

Thanks @aborgna-q - Lemme just check why the roundtrip schema validation wasn't catching my change, because this looks like the same check...

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 1 line in your changes missing coverage. Please review.

Project coverage is 82.01%. Comparing base (0280eb2) to head (e90dc84).

Files with missing lines	Patch %	Lines
hugr-core/src/envelope/package_json.rs	80.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2216   +/-   ##
=======================================
  Coverage   82.00%   82.01%           
=======================================
  Files         230      230           
  Lines       40940    40951   +11     
  Branches    37041    37052   +11     
=======================================
+ Hits        33574    33584   +10     
- Misses       5398     5399    +1     
  Partials     1968     1968           

Flag	Coverage Δ
python	85.63% <ø> (ø)
rust	81.62% <90.90%> (+<0.01%)	⬆️

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[acl-cqc]

Yeah, so see https://github.com/CQCL/hugr/actions/runs/15024222682, passing on the last commit (20bd6a7) on branch acl/schema_test. So whilst I am minded to approve this PR as is (that is - this PR doesn't look like it introduces too much overhead to me!), clearly schema validation is not doing what I think it should...

[aborgna-q]

So whilst I am minded to approve this PR as is (that is - this PR doesn't look like it introduces too much overhead to me!)

So, should we merge it?

[acl-cqc]

So, should we merge it?

I think we should understand why these kind of checks don't catch the malformed json's mentioned above; if these aren't schema violations, why not / what are they?

Thinking we have schema checks when actually they don't catch what look to me like schema errors, could well be worse than knowing we don't have schema checks....