Add repository agent profiles

[johnnygreco]

Summary

• add a reusable dev-tools/agents framework for repository-owned OpenShell agent profiles
• keep OpenShell lifecycle in a readable shell launcher and use one standalone, locked Python helper for structured-data validation and file generation
• add a pinned Pi print-mode harness, independent inference-provider configuration, and the initial Dev Note reviewer profile
• add path-scoped CI covering the helper lock, unit tests, lint/format checks, shell syntax, staging, and the Pi container build

Why

The agent runtime should be established and reviewed independently before Slop Cop consumes it. This PR intentionally contains no Slop Cop workflows or integration changes.

Validation

• uv lock --script helpers.py --check
• python3 -m unittest discover -s tests -v (4 tests)
• Ruff lint and formatting checks
• Python compile checks
• Bash syntax checks
• YAML parsing for the new workflow
• git diff --check

The local Docker build reached the pinned Docker Hub image lookup but the current environment's Docker proxy DNS could not resolve its proxy host. The path-scoped GitHub Actions job performs the complete staged Pi image build.