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/bulk-delete-css-templates.api.mdx

@@ -0,0 +1,68 @@
+---
+id: bulk-delete-css-templates
+title: "Bulk delete CSS templates"
+description: "Bulk delete CSS templates"
+sidebar_label: "Bulk delete CSS templates"
+hide_title: true
+hide_table_of_contents: true
+api: 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
+sidebar_class_name: "delete 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={"Bulk delete CSS templates"}
+>
+</Heading>
+
+<MethodEndpoint
+  method={"delete"}
+  path={"/api/v1/css_template/"}
+  context={"endpoint"}
+>
+
+</MethodEndpoint>
+
+
+
+Bulk delete CSS templates
+
+<Heading
+  id={"request"}
+  as={"h2"}
+  className={"openapi-tabs__heading"}
+>
+  <Translate id="theme.openapi.request.title">Request</Translate>
+</Heading>
+
+<ParamsDetails
+  {...require("./bulk-delete-css-templates.ParamsDetails.json")}
+>
+
+</ParamsDetails>
+
+<RequestSchema
+  {...require("./bulk-delete-css-templates.RequestSchema.json")}
+>
+
+</RequestSchema>
+
+<StatusCodes
+  {...require("./bulk-delete-css-templates.StatusCodes.json")}
+>
+
+</StatusCodes>