feat(governance): update governance rules to use domain tech councils

[damaz91]

Description

Update the UCP clearance hierarchy across all repository governance rules to transition from the single legacy tech-council team to the domain-specific Technical Councils (shopping-tech-council, food-tech-council, lodging-tech-council, and payments-tech-council) at Level 3.

Key changes:

• team_hierarchy updates: Updated all 8 governance rules files (ucp-rules.yml, .github-rules.yml, conformance-rules.yml, js-sdk-rules.yml, meeting-minutes-rules.yml, python-sdk-rules.yml, samples-rules.yml, and ucp-schema-rules.yml) to define shopping-tech-council, food-tech-council, lodging-tech-council, and payments-tech-council at Level 3.
• meeting-minutes-rules.yml: Updated the tech_council_minutes rule from min_team: "tech-council" to min_team: "shopping-tech-council".
• pr_validator.py: Added graceful handling for HTTP 404 (team not found) when querying GitHub team memberships. This logs a warning and treats the team as empty rather than raising an unhandled exception, ensuring resilience during team migrations.
• Documentation: Updated org-tools/governance/README.md and org-tools/governance/docs/validation_report.md to reflect the domain Tech Councils hierarchy.
• Tests: Added unit test test_fetch_team_not_found_handled in test_pr_validator.py.

Category (Required)

• 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

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.
• 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.

[ptiper]

LGTM overall, thanks for adding the graceful 404 handling and adding the Domain Tech Councils to the clearance hierarchy! Approving, with a couple of suggestions for meeting-minutes-rules.yml:

1. Domain-specific rules: Rather than routing all tc/** to shopping-tech-council, let's break this into vertical-specific rules (tc/shopping/, tc/food/, tc/lodging/, tc/payments/) now that PR #35 has organized the folder structure by council. This ensures the bot's PR status comment asks for approval from the correct domain council instead of directing everyone to shopping-tech-council. Shared templates (tc/*.md) can fall back to devops-maintainers.
2. Retain tech-council: 3 in team_hierarchy: Consider keeping tech-council: 3 in team_hierarchy across the rule sets during the transition. meeting-minutes/.github/CODEOWNERS still points /tc/ to @Universal-Commerce-Protocol/tech-council, and removing it from team_hierarchy causes pr_validator.py to drop those assigned reviewers and report 0 eligible reviewers assigned. Once this PR lands, we can update CODEOWNERS in meeting-minutes to point to each domain team.