feat(agents): establish release management standards and release-management skill

[MichalRedm]

Summary

• Established formal agent governance rules and guidelines for package versioning, changelog maintenance, and PyPI release management in STRIDE.
• Introduced .agents/rules/release_standards.md codifying Semantic Versioning (MAJOR.MINOR.PATCH) criteria, release triggers, pre-release invariants, and PyPI OIDC trusted publishing protocols.
• Added .agents/skills/release-management/SKILL.md enabling agents to autonomously evaluate version increments, maintain CHANGELOG.md, run distribution packaging checks (build & twine), draft GitHub Releases via gh release create, and monitor PyPI deployment workflows.
• Integrated the new standards and skill into the Master Rule Routing Matrix in AGENTS.md and machine-readable schema acs.yaml.
• Updated roadmap status in .agents/project_context.md.

Motivation

Following the implementation of automated PyPI OIDC Trusted Publishing (#10) and the merge of the Shaker semi-synthetic drift protocol (#11), strict guidelines are necessary to ensure consistent SemVer versioning, prevent release desynchronization, and provide standard operating procedures for future automated and human releases.

Key Changes

1. Agent Governance & Declarative Standards

• .agents/rules/release_standards.md: Defines SemVer conditions (MAJOR, MINOR, PATCH), pre-release checklist (clean origin/main, version synchronization in src/stride/__init__.py, CHANGELOG.md entry, twine check --strict), and publication protocols.
• AGENTS.md: Added Releases & PyPI Publishing row to the Mandatory Rule Routing Matrix.
• .agents/acs.yaml: Configured trigger paths for release_standards.md and release-management skill.

2. Operational Agent Skill

• .agents/skills/release-management/SKILL.md: 5-step operational workflow covering commit history inspection since last tag, version bump PR preparation, local wheel/sdist build validation, release notes creation using temporary files, and CI run monitoring.

Verification

• ruff check . passed with 0 errors
• ruff format --check . passed cleanly (112 files formatted)
• python -m unittest discover tests passed with 42/42 tests passing in 14.8s