Clarify scaffold structural folders

[abhinavgautam01]

Summary

Clarifies that workspace.folders is not an exhaustive allowlist of every directory created by maxed init.

maxed init still creates suite structural folders for generated config, example workpapers, fixtures and the runnable pipeline, even when a user provides a custom workspace.folders list.

Changes

• Updated the workspace.folders schema description
• Added README wording explaining the structural folders created by init
• Added a regression test covering custom folders plus required suite scaffold files

Validation

• pytest -q
• git diff --check
• maxed --version
• maxed suite --json
• maxed init examples/workspace.yaml --base-dir /tmp/maxed-cli-docs-ci-smoke --json
• maxed lint-workpaper /tmp/maxed-cli-docs-ci-smoke/example-workspace/workpapers/example.workpaper.json
• Package build
• Built wheel install + maxed --version