docs: run tests in the uv environment

[FanouZeng-TT]

Description

The development setup installs the project and its dependencies with uv sync, but the documented test command invokes python directly:

uv sync
python -m unittest discover -s tests -p "test_*.py"

On a system where python resolves outside .venv, that command still exits successfully while skipping the SDK-dependent semantic tests. In a clean checkout, /usr/bin/python3 reported OK (skipped=29), while the same suite through uv ran all 79 tests without skips.

Fix: run the documented test command with uv run python, matching the environment created by the setup instructions.

Category (Required)

• Core Protocol: Changes to the protocol specification. (Requires Technical Council approval)
• Governance/Contributing: Changes to governance or contributing documentation. (Requires Governance Council approval)
• Capability: Changes to an existing capability. (Requires Maintainer approval)
• Documentation: Documentation-only changes. (Requires Maintainer approval)
• Infrastructure: CI/CD, build, or deployment changes. (Requires DevOps Maintainer approval)
• Maintenance: Dependency or repository maintenance. (Requires DevOps Maintainer approval)
• SDK: Language-specific SDK updates and releases. (Requires DevOps Maintainer approval)
• Samples / Conformance: Maintaining samples and the conformance suite. (Requires Maintainer approval)
• UCP Schema: Changes to the ucp-schema tool. (Requires Maintainer approval)
• Community Health (.github): Organization-wide community files. (Requires DevOps Maintainer approval)

Related Issues

N/A

Checklist

• I have followed the Contributing Guide (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. (The existing suite demonstrates the environment difference.)
• 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. (Not applicable; no generator or model changes.)

Screenshots / Logs (if applicable)

/usr/bin/python3: Ran 79 tests — OK (skipped=29)
uv run python: Ran 79 tests — OK
pre-commit: 12 hooks passed