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/index.md

@@ -0,0 +1,135 @@
+---
+title: Overview
+sidebar_position: 1
+---
+
+<!--
+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.
+-->
+
+# Developer Docs
+
+Welcome to the Apache Superset Developer Docs - your comprehensive resource for contributing to and extending Apache Superset.
+
+## Quick Start
+
+### New Contributors
+- [Contributing Overview](/developer-docs/contributing/overview)
+- [Development Setup](/developer-docs/contributing/development-setup)
+- [Your First PR](/developer-docs/contributing/submitting-pr)
+
+### Extension Development
+- [Extension Development](/developer-docs/extensions/development)
+- [Extension Architecture](/developer-docs/extensions/architecture)
+- [Quick Start](/developer-docs/extensions/quick-start)
+
+## Documentation Sections
+
+### Extensions
+Learn how to build powerful extensions that enhance Superset's capabilities. This section covers the extension architecture, development patterns, and deployment strategies. You'll find comprehensive guides on creating frontend contributions, managing extension lifecycles, and understanding security implications.
+
+### Testing
+Comprehensive testing strategies for Superset development. This section covers frontend testing with Jest and React Testing Library, backend testing with pytest, end-to-end testing with Playwright, and CI/CD pipeline best practices.
+
+### Contributing to Superset
+Everything you need to contribute to the Apache Superset project. This section includes community guidelines, development environment setup, pull request processes, code review workflows, issue reporting guidelines, and Apache release procedures. You'll also find style guidelines for both frontend and backend development.
+
+## Development Resources
+
+### Prerequisites
+- **Python**: 3.9, 3.10, or 3.11
+- **Node.js**: 18.x or 20.x
+- **npm**: 9.x or 10.x
+- **Git**: Basic understanding
+- **React/TypeScript**: For frontend development
+- **Flask/SQLAlchemy**: For backend development
+
+### Key Technologies
+- **Frontend**: React, TypeScript, Ant Design, Redux
+- **Backend**: Flask, SQLAlchemy, Celery, Redis
+- **Build Tools**: Webpack, Babel, npm/yarn
+- **Testing**: Jest, Pytest, Playwright
+- **CI/CD**: GitHub Actions, pre-commit
+
+## Community
+
+### Get Help
+- **[Slack](https://apache-superset.slack.com)** - Join #development, #troubleshooting, or #beginners
+- **[GitHub Discussions](https://github.com/apache/superset/discussions)** - Ask questions and share ideas
+- **[Mailing Lists](https://lists.apache.org/list.html?dev@superset.apache.org)** - Development discussions
+
+### Contribute
+- **[Good First Issues](https://github.com/apache/superset/labels/good%20first%20issue)** - Start here!
+- **[Help Wanted](https://github.com/apache/superset/issues?q=is%3Aissue+is%3Aopen+label%3A%22help+wanted%22)** - Issues needing help
+- **[Roadmap](https://github.com/orgs/apache/projects/180)** - See what's planned
+
+## Additional Resources
+
+### External Documentation
+- **[User Documentation](https://superset.apache.org/docs/intro)** - Using Superset
+- **[API Documentation](/developer-docs/api)** - REST API reference
+- **[Configuration Guide](https://superset.apache.org/admin-docs/configuration/configuring-superset)** - Setup and configuration
+
+### Important Files
+- **[CLAUDE.md](https://github.com/apache/superset/blob/master/CLAUDE.md)** - LLM development guide
+- **[UPDATING.md](https://github.com/apache/superset/blob/master/UPDATING.md)** - Breaking changes log
+
+## Where to Start?
+
+<table>
+<tr>
+<td width="50%">
+
+**I want to contribute code**
+1. [Set up development environment](/developer-docs/contributing/development-setup)
+2. [Find a good first issue](https://github.com/apache/superset/labels/good%20first%20issue)
+3. [Submit your first PR](/developer-docs/contributing/submitting-pr)
+
+</td>
+<td width="50%">
+
+**I want to build an extension**
+1. [Start with Quick Start](/developer-docs/extensions/quick-start)
+2. [Learn extension development](/developer-docs/extensions/development)
+3. [Explore architecture](/developer-docs/extensions/architecture)
+
+</td>
+</tr>
+<tr>
+<td>
+
+**I found a bug**
+1. [Search existing issues](https://github.com/apache/superset/issues)
+2. [Report the bug](/developer-docs/contributing/issue-reporting)
+3. [Submit a fix](/developer-docs/contributing/submitting-pr)
+
+</td>
+<td>
+
+**I need help**
+1. [Check the FAQ](https://superset.apache.org/docs/frequently-asked-questions)
+2. [Ask in Slack](https://apache-superset.slack.com)
+3. [Start a discussion](https://github.com/apache/superset/discussions)
+
+</td>
+</tr>
+</table>
+
+---
+
+Welcome to the Apache Superset community! We're excited to have you contribute.