docs: harden TalkEd repo guidance and hygiene checks

[th3w1zard1]

Summary

• align TalkEd docs with the current ignored-artifact policy for Delphi companion files
• add a lightweight repository-hygiene workflow for markdown, JSON, YAML, and ignore-policy checks
• document current label baseline and the private-repo branch-protection limitation

Validation

• npx --yes markdownlint-cli@0.45.0 "**/*.md" --ignore node_modules
• verified .github/workflows/repo-hygiene.yml parses cleanly
• verified representative ignored artifacts resolve through git check-ignore --stdin

Notes

• branch protection is still blocked by the current GitHub private-repo plan tier and is documented rather than misrepresented as active
• UI/resource artifacts remain uncommitted per repository policy and explicit session instruction

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.