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/export-all-assets.api.mdx

@@ -0,0 +1,58 @@
+---
+id: export-all-assets
+title: "Export all assets"
+description: "Gets a ZIP file with all the Superset assets (databases, datasets, charts, dashboards, saved queries) as YAML files."
+sidebar_label: "Export all assets"
+hide_title: true
+hide_table_of_contents: true
+api: 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
+sidebar_class_name: "get api-method"
+info_path: developer-docs/api/superset
+custom_edit_url: null
+hide_send_button: true
+show_extensions: true
+---
+
+import MethodEndpoint from "@theme/ApiExplorer/MethodEndpoint";
+import ParamsDetails from "@theme/ParamsDetails";
+import RequestSchema from "@theme/RequestSchema";
+import StatusCodes from "@theme/StatusCodes";
+import OperationTabs from "@theme/OperationTabs";
+import TabItem from "@theme/TabItem";
+import Heading from "@theme/Heading";
+import Translate from "@docusaurus/Translate";
+
+<Heading
+  as={"h1"}
+  className={"openapi__heading"}
+  children={"Export all assets"}
+>
+</Heading>
+
+<MethodEndpoint
+  method={"get"}
+  path={"/api/v1/assets/export/"}
+  context={"endpoint"}
+>
+
+</MethodEndpoint>
+
+
+
+Gets a ZIP file with all the Superset assets (databases, datasets, charts, dashboards, saved queries) as YAML files.
+
+<ParamsDetails>
+
+</ParamsDetails>
+
+<RequestSchema
+  {...require("./export-all-assets.RequestSchema.json")}
+>
+
+</RequestSchema>
+
+<StatusCodes
+  {...require("./export-all-assets.StatusCodes.json")}
+>
+
+</StatusCodes>