Teach generated workspaces about local overrides

[cbusillo]

Summary

• link generated cockpit and tenant workspace guides to optional local AGENTS.override.md files for non-secret operator facts
• replace stale Harbor wording with Launchplane in generated defaults and tenant overlay templates
• mark state/ as legacy or disposable local runtime output and fix generated cockpit commands to use uv --project

Validation

• uv run ruff check .
• uv run python -m unittest discover -s tests -p 'test_*.py'
• git diff --check
• uv --project sources/devkit run platform workspace status-cockpit-root --config workspace-cockpit.toml