feat: add commit message standardization (#36)

[c-vigo]

Pull Request

Description

This PR merges commit message standardization (#36) into the automate-repository-setup branch (#37). It adds a documented commit message format, validation (Python script + commit-msg hook), Cursor integration, and workspace template updates so new repos get the same standard.

Related Issue(s)

Closes #36
Related to #37

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Test updates

Changes Made

• Commit message standard — docs/COMMIT_MESSAGE_STANDARD.md and workspace copy: format type(scope)!: subject, mandatory Refs: #<issue>, approved types, traceability (REQ-/RISK-/SOP-).
• Validation — scripts/validate_commit_msg.py: validates subject, blank line, single Refs line with at least one #issue; used by commit-msg hook and tests.
• Commit-msg hook — .githooks/commit-msg (repo and assets/workspace/.githooks/commit-msg): runs validation; workspace hook checks IN_CONTAINER and calls validator.
• Pre-commit — commit-msg stage in .pre-commit-config.yaml (repo) and workspace pre-commit config: validate-commit-msg hook.
• Init — scripts/init.sh: sets core.hooksPath .githooks, chmod +x for pre-commit and commit-msg, and commit.template .gitmessage.
• Template — .gitmessage (repo and workspace): subject + Refs placeholder.
• Cursor — .cursor/rules/commit-messages.mdc, .cursor/commands/commit-msg.md (repo and workspace): rules and slash command for commit workflow.
• Workspace — assets/workspace/.devcontainer/scripts/setup-git-conf.sh: sets commit.template when .gitmessage exists.
• Tests — tests/test_validate_commit_msg.py: valid/invalid messages; integration tests for commit-msg hook in workspace.
• Docs — README/CONTRIBUTE: test-validate-commit-msg, commit standard reference.

Testing

• Tests pass locally (just test)
• Manual testing performed (describe below)

Manual Testing Details

• just test-validate-commit-msg passes.
• Commit with invalid message (e.g. git commit -m "invalid") is rejected by commit-msg hook.
• Commit with valid message (e.g. feat: add x + blank line + Refs: #36) is accepted.

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly (README.md, CONTRIBUTE.md, etc.)
• I have updated the CHANGELOG.md in the [Unreleased] section
• My changes generate no new warnings or errors
• 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
• Any dependent changes have been merged and published

Additional Notes

• Base branch: feature/37-automate-standardize-repository-setup
• No reviewer requested; remove assignees if added by default.