feat(language): preserve hgraph IR contracts

[hhenson]

Summary

• lower normalized generic constraints into a self-contained hgraph-IR arena
• preserve effective nominal struct contracts, inherited field origins, defaults, and optionality
• attach requirements to struct, operator, and callable interfaces while keeping nominal and native registry identities distinct
• extend the deterministic hgraph-IR dump, architecture documentation, and focused coverage

Validation

• clang-format dry run on changed C++ files
• git diff --check
• complete language CTest suite: 29/29 passed
• clean native configure, rebuild, and CTest suite: 1711/1711 passed
• stable-ABI wheel built with Python 3.12 and complete non-WIP compatibility suite run from a fresh Python 3.14 environment: 3223 passed, 10 skipped

Stacked on #690.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-05T15:12:50.229151Z	d73ea85	PR opened
🔒 Security Review	✅ Completed 2026-09-05T15:10:56.216308Z	d73ea85	PR opened

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[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: d73ea859e7

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud