docs(agent): improve repository guidance [skip ci] (#685)

- Add canonical agent and contributor documentation.

- Modernize issue and pull request templates.

- Skip CI for documentation and issue-template-only changes.

.github/workflows/ci.yml

@@ -14,6 +14,7 @@ on:
       - '**/FUNDING.yml'
       - '**/host.ini'
       - '**/*.md'
+      - '.github/ISSUE_TEMPLATE/**'
       - '**/.editorconfig'
       - '**/ansible.example.cfg'
       - '**/deploy.sh'