fix: scope uniqueItems validators to declaring classes

[horaceewang-TT]

Description

Scopes uniqueItems validators to the generated classes that declare the constraint.

Previously, validators were matched globally by field name, causing unrelated classes with same-named list fields to receive validators incorrectly. Schema scanning now preserves class ownership, and regression tests verify that only the declaring class is patched.

Category (Required)

• Maintenance: Version bumps, lockfile updates, or minor bug fixes.
• SDK: Language-specific SDK updates and releases.

Related Issues

#60

Checklist

• I have followed the https://github.com/Universal-Commerce-Protocol/.github/blob/main/CONTRIBUTING.md (including Conventional Commits title requirements and ! for breaking changes).
• I have updated the documentation (if applicable).
• My changes pass all local linting and formatting checks.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• (For Core/Capability) I have included/updated the relevant JSON schemas.
• I have regenerated Python Pydantic models by running generate_models.sh under python_sdk.

Screenshots / Logs (if applicable)

Ran 45 tests in 0.029s.

OK (skipped=15)

Formatting and linting checks passed.

Runtime verification:

• First.tags rejects duplicate values with a ValidationError.
• Second.tags accepts duplicate values because it does not declare uniqueItems.
• Exactly one uniqueItems validator is injected.

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