docs: cut 6.1.0 versions for docs, admin_docs, developer_docs, components

- Snapshot all four versioned docs sections at v6.1.0; master continues to
  serve as "Next" (lastVersion: current, banner: unreleased) so editing
  master keeps updating the canonical URLs
- Enable the previously-disabled components plugin and version it
- Rename stale "developer_portal" references to "developer_docs" across
  package.json scripts, manage-versions.mjs, theme files (DocVersionBadge,
  DocVersionBanner), DOCS_CLAUDE.md, and README.md (URL backward-compat
  redirect /developer_portal/* preserved)
- Add admin_docs version scripts; drop dead "tutorials" plugin id from
  the version badge
- Generalize fixVersionedImports in manage-versions.mjs to walk every
  section's snapshot and rewrite ../../src/ and ../../data/ imports,
  catching admin_docs and components files that previous version cuts
  would have broken
- Remove orphan files: developer_portal_versions.json,
  tutorials_versions.json, and stray empty versions.json files inside
  components/ and developer_docs/ content directories

docs/developer_docs_versioned_docs/version-6.1.0/api/schemas/dashboardcopyschema.Schema.json

@@ -0,0 +1 @@
+{"schema":{"properties":{"css":{"description":"Override CSS for the dashboard.","type":"string"},"dashboard_title":{"description":"A title for the dashboard.","maxLength":500,"minLength":0,"nullable":true,"type":"string"},"duplicate_slices":{"description":"Whether or not to also copy all charts on the dashboard","type":"boolean"},"json_metadata":{"description":"This JSON object is generated dynamically when clicking the save or overwrite button in the dashboard view. It is exposed here for reference and for power users who may want to alter  specific parameters.","type":"string"}},"required":["json_metadata"],"type":"object","title":"DashboardCopySchema"},"schemaType":"response"}