fix(governance): include missing files across js-sdk, ucp, and .github rules

[ptiper]

Description

Fix governance rule omissions across repositories to ensure 100% coverage and avoid unexpected fallback triggers (which require Governance Council approval):

1. js-sdk (js-sdk-rules.yml): Add tests/** under infra_and_tooling.patterns. Currently, modifying test files (such as tests/spec-constraints.test.js) falls back to the catch-all rule.
2. ucp (ucp-rules.yml): Add README.md under infra_and_tooling.patterns (aligning with all other UCP repositories).
3. .github (.github-rules.yml): Add DOMAIN_WORKING_GROUP_CHARTER.md under governance.patterns alongside DOMAIN_TECH_COUNCIL_CHARTER.md.

With these updates, static coverage analysis (validate_no_fallback) achieves 100% across all 8 active UCP repositories (966 tracked files scanned with 0 unhandled fallbacks).

Category (Required)

Please select one or more categories that apply to this change.

• Core Protocol: Changes to the base communication layer, global context, or breaking refactors. (Requires Technical Council approval)
• Governance/Contributing: Updates to GOVERNANCE.md, CONTRIBUTING.md, or CODEOWNERS. (Requires Governance Council approval)
• Capability: New schemas (Discovery, Cart, etc.) or extensions. (Requires Maintainer approval)
• Documentation: Updates to README, or documentations regarding schema or capabilities. (Requires Maintainer approval)
• Infrastructure: CI/CD, Linters, or build scripts. (Requires DevOps Maintainer approval)
• Maintenance: Version bumps, lockfile updates, or minor bug fixes. (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 (resolver, linter, validator). (Requires Maintainer approval)
• Community Health (.github): Updates to templates, workflows, or org-level configs. (Requires DevOps Maintainer approval)

Related Issues

None

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.
• 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)

Unit tests in .github:

Ran 64 tests in 0.040s
OK

No-fallback coverage check across all 8 repos (966 files total):

• js-sdk: 0 fallback files
• python-sdk: 0 fallback files
• ucp: 0 fallback files
• ucp-schema: 0 fallback files
• conformance: 0 fallback files
• samples: 0 fallback files
• meeting-minutes: 0 fallback files
• .github: 0 fallback files