Adds `docs/PLUGIN_AUTHORING.md` documenting the `executorRuntimeEnv` hook with cross-references to the architecture docs, accompanied by tests validating the documentation contract.
Fusion-Task-Id: FN-3967
- Create a disposable HOME/USERPROFILE env for scripts/test-changed.mjs execution
- Run isolation guard checks with the same isolated env, including cache-hit no-op paths
- Clean up temp HOME after test execution to avoid residue
- Update test coverage and contributing docs for the shared isolation behavior
Fusion-Task-Id: FN-3610
- Add missing top-level dashboard views section to the PLUGIN_AUTHORING table of contents
- Renumber downstream section headings and TOC entries to keep numbering sequential
- Add a node:test suite that validates heading order and TOC anchor alignment
Fusion-Task-Id: FN-3468
