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

Snapshots all four versioned Docusaurus sections at v6.1.0. Built on
top of the version-cutting tooling work in chore/docs-cut-6.1.0-versions
so the snapshot benefits from:

- Auto-gen refresh before snapshotting (database pages from engine
  spec metadata, API reference from openapi.json, component pages
  from Storybook stories) — captured at the SHA we cut from rather
  than whatever happened to be on disk.
- Data-import freeze: country list, feature flag table, database
  diagnostics, and component metadata are copied into snapshot-local
  `_versioned_data/` dirs so the historical version doesn't silently
  mutate when the source files change.
- Depth-aware import-path rewriter that handles deeply-nested
  component MDX files referencing `../../../src/` from the snapshot.

Versioning behavior: `lastVersion` stays at `current` for every
section, so the canonical URLs (`/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. The plugin block in docusaurus.config.ts
was already gated only by the `disabled` flag, so no other code
changes were needed to bring it back online.

The frozen `databases.json` in the snapshot is the canonical 80-database
artifact from the latest committed state in master (preserved by the
generator's input-hash cache), not a fallback regenerated from a
local Flask environment.

docs/developer_docs_versioned_docs/version-6.1.0/components/index.mdx

@@ -0,0 +1,70 @@
+---
+title: UI Components Overview
+sidebar_label: Overview
+sidebar_position: 0
+---
+
+<!--
+    Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you under the Apache License, Version 2.0 (the
+    "License"); you may not use this file except in compliance
+    with the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing,
+    software distributed under the License is distributed on an
+    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+    KIND, either express or implied.  See the License for the
+    specific language governing permissions and limitations
+    under the License.
+-->
+
+import { ComponentIndex } from '@site/src/components/ui-components';
+import componentData from '../_versioned_data/static/data/components.json';
+
+# UI Components
+
+<ComponentIndex data={componentData} />
+
+---
+
+## Design System
+
+A design system is a complete set of standards intended to manage design at scale using reusable components and patterns.
+
+The Superset Design System uses [Atomic Design](https://bradfrost.com/blog/post/atomic-web-design/) principles with adapted terminology:
+
+| Atomic Design | Atoms | Molecules | Organisms | Templates | Pages / Screens |
+|---|:---:|:---:|:---:|:---:|:---:|
+| **Superset Design** | Foundations | Components | Patterns | Templates | Features |
+
+<img src="/img/atomic-design.png" alt="Atoms = Foundations, Molecules = Components, Organisms = Patterns, Templates = Templates, Pages / Screens = Features" style={{maxWidth: '100%'}} />
+
+## Usage
+
+All components are exported from `@superset-ui/core/components`:
+
+```tsx
+import { Button, Modal, Select } from '@superset-ui/core/components';
+```
+
+## Contributing
+
+This documentation is auto-generated from Storybook stories. To add or update component documentation:
+
+1. Create or update the component's `.stories.tsx` file
+2. Add a descriptive `title` and `description` in the story meta
+3. Export an interactive story with `args` for configurable props
+4. Run `yarn generate:superset-components` in the `docs/` directory
+
+:::info Work in Progress
+This component library is actively being documented. See the [Components TODO](./TODO) page for a list of components awaiting documentation.
+:::
+
+---
+
+*Auto-generated from Storybook stories in the [Design System/Introduction](https://github.com/apache/superset/blob/master/superset-frontend/packages/superset-ui-core/src/components/DesignSystem.stories.tsx) story.*