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/clear-the-system-dark-theme.api.mdx

@@ -0,0 +1,58 @@
+---
+id: clear-the-system-dark-theme
+title: "Clear the system dark theme"
+description: "Clear the system dark theme"
+sidebar_label: "Clear the system dark theme"
+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={"Clear the system dark theme"}
+>
+</Heading>
+
+<MethodEndpoint
+  method={"delete"}
+  path={"/api/v1/theme/unset_system_dark"}
+  context={"endpoint"}
+>
+
+</MethodEndpoint>
+
+
+
+Clear the system dark theme
+
+<ParamsDetails>
+
+</ParamsDetails>
+
+<RequestSchema
+  {...require("./clear-the-system-dark-theme.RequestSchema.json")}
+>
+
+</RequestSchema>
+
+<StatusCodes
+  {...require("./clear-the-system-dark-theme.StatusCodes.json")}
+>
+
+</StatusCodes>