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

Snapshots all four versioned Docusaurus sections at v6.1.0, cut from
master after the version-cutting tooling (#39837), broken-internal-
links fix (#40102), and user_docs rename (#40171) all landed. With
the rename in place, all four sections now produce parallel-named
files at the docs/ root (no more bare `versioned_docs/` outlier).

Versioning behavior: lastVersion stays at current for every section,
so the canonical URLs (/user-docs/..., /admin-docs/...,
/developer-docs/..., /components/...) continue to render content
from master. The current version is consistently labeled "Next"
with an unreleased banner, and 6.1.0 is a historical pin accessible
only via its explicit version segment.

Component playground: previously disabled: true in versions-config.json,
now enabled and versioned.

Snapshot includes:
- All MDX content for the four sections.
- Auto-gen captured fresh: 74 database pages (engine spec metadata),
  ~1,800 API reference files (openapi.json), 59 component pages
  (Storybook stories).
- Data imports frozen at cut time into snapshot-local _versioned_data/
  dirs:
    user_docs_versioned_docs/version-6.1.0/_versioned_data/src/data/databases.json
      (canonical 80-database diagnostics from master, preserved by the
      generator's input-hash cache)
    admin_docs_versioned_docs/version-6.1.0/_versioned_data/data/countries.json
    admin_docs_versioned_docs/version-6.1.0/_versioned_data/static/feature-flags.json
    developer_docs_versioned_docs/version-6.1.0/_versioned_data/static/data/components.json
- Import paths in deeply-nested files rewritten so they still resolve
  from one directory deeper inside the snapshot.
- developer_docs/extensions/overview.md snapshot has the FIXED
  ./mcp.md form (from #40102), so the SPA-nav 404 isn't baked into
  the 6.1.0 version.

Verified via full yarn build: exit 0, no broken links surfaced by
onBrokenLinks: throw.

docs/developer_docs_versioned_docs/version-6.1.0/api/get-a-theme.StatusCodes.json

@@ -0,0 +1 @@
+{"responses":{"200":{"content":{"application/json":{"schema":{"properties":{"description_columns":{"properties":{"column_name":{"description":"The description for the column name. Will be translated by babel","example":"A Nice description for the column","type":"string"}},"type":"object"},"id":{"description":"The item id","type":"string"},"label_columns":{"properties":{"column_name":{"description":"The label for the column name. Will be translated by babel","example":"A Nice label for the column","type":"string"}},"type":"object"},"result":{"properties":{"changed_by":{"properties":{"first_name":{"maxLength":64,"type":"string"},"id":{"type":"integer"},"last_name":{"maxLength":64,"type":"string"}},"required":["first_name","last_name"],"type":"object","title":"ThemeRestApi.get.User"},"changed_on_delta_humanized":{"readOnly":true},"created_by":{"properties":{"first_name":{"maxLength":64,"type":"string"},"id":{"type":"integer"},"last_name":{"maxLength":64,"type":"string"}},"required":["first_name","last_name"],"type":"object","title":"ThemeRestApi.get.User1"},"id":{"type":"integer"},"is_system":{"type":"boolean"},"is_system_dark":{"type":"boolean"},"is_system_default":{"type":"boolean"},"json_data":{"nullable":true,"type":"string"},"theme_name":{"maxLength":250,"nullable":true,"type":"string"},"uuid":{"format":"uuid","nullable":true,"type":"string"}},"type":"object","title":"ThemeRestApi.get"},"show_columns":{"description":"A list of columns","items":{"type":"string"},"type":"array"},"show_title":{"description":"A title to render. Will be translated by babel","example":"Show Item Details","type":"string"}},"type":"object"},"example":{"description_columns":{"column_name":"A Nice description for the column"},"id":"string","label_columns":{"column_name":"A Nice label for the column"},"result":{"changed_on_delta_humanized":{},"id":1,"is_system":true,"is_system_dark":true,"is_system_default":true,"json_data":"string","theme_name":"string","uuid":"550e8400-e29b-41d4-a716-446655440000"},"show_columns":["string"],"show_title":"Show Item Details"}}},"description":"Item from Model"},"400":{"content":{"application/json":{"schema":{"properties":{"message":{"type":"string"}},"type":"object"},"example":{"message":"Bad request: Invalid parameters provided"}}},"description":"Bad request"},"401":{"content":{"application/json":{"schema":{"properties":{"message":{"type":"string"}},"type":"object"},"example":{"message":"Unauthorized: Authentication required"}}},"description":"Unauthorized"},"404":{"content":{"application/json":{"schema":{"properties":{"message":{"type":"string"}},"type":"object"},"example":{"message":"Not found: The requested resource does not exist"}}},"description":"Not found"},"422":{"content":{"application/json":{"schema":{"properties":{"message":{"type":"string"}},"type":"object"},"example":{"message":"Unprocessable entity: Validation error"}}},"description":"Could not process entity"},"500":{"content":{"application/json":{"schema":{"properties":{"message":{"type":"string"}},"type":"object"},"example":{"message":"Internal server error: An unexpected error occurred"}}},"description":"Fatal error"}}}