docs: cut 6.1.0 versions for 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) and broken-internal-
links fixes (#40102) landed. Captures fresh auto-generated content and
freezes data dependencies so the historical snapshot stays correct.

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.

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:
    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.

Verified via full yarn build: exit 0, no broken links surfaced by
onBrokenLinks: throw. Anchor warnings present are pre-existing on
master (community#superset-community-calendar) and unrelated.

docs/developer_docs_versioned_docs/version-6.1.0/api/schemas/dataset.Schema.json

@@ -0,0 +1 @@
+{"schema":{"properties":{"cache_timeout":{"description":"Duration (in seconds) of the caching timeout for this dataset.","type":"integer"},"column_formats":{"description":"Column formats.","type":"object"},"columns":{"description":"Columns metadata.","items":{"type":"object"},"type":"array"},"database":{"description":"Database associated with the dataset.","type":"object"},"datasource_name":{"description":"Dataset name.","type":"string"},"default_endpoint":{"description":"Default endpoint for the dataset.","type":"string"},"description":{"description":"Dataset description.","type":"string"},"edit_url":{"description":"The URL for editing the dataset.","type":"string"},"extra":{"description":"JSON string containing extra configuration elements.","type":"object"},"fetch_values_predicate":{"description":"Predicate used when fetching values from the dataset.","type":"string"},"filter_select":{"description":"SELECT filter applied to the dataset.","type":"boolean"},"filter_select_enabled":{"description":"If the SELECT filter is enabled.","type":"boolean"},"granularity_sqla":{"description":"Name of temporal column used for time filtering for SQL datasources. This field is deprecated, use `granularity` instead.","items":{"items":{"type":"object"},"type":"array"},"type":"array"},"health_check_message":{"description":"Health check message.","type":"string"},"id":{"description":"Dataset ID.","type":"integer"},"is_sqllab_view":{"description":"If the dataset is a SQL Lab view.","type":"boolean"},"main_dttm_col":{"description":"The main temporal column.","type":"string"},"metrics":{"description":"Dataset metrics.","items":{"type":"object"},"type":"array"},"name":{"description":"Dataset name.","type":"string"},"offset":{"description":"Dataset offset.","type":"integer"},"order_by_choices":{"description":"List of order by columns.","items":{"items":{"type":"string"},"type":"array"},"type":"array"},"owners":{"description":"List of owners identifiers","items":{"type":"integer"},"type":"array"},"params":{"description":"Extra params for the dataset.","type":"object"},"perm":{"description":"Permission expression.","type":"string"},"schema":{"description":"Dataset schema.","type":"string"},"select_star":{"description":"Select all clause.","type":"string"},"sql":{"description":"A SQL statement that defines the dataset.","type":"string"},"table_name":{"description":"The name of the table associated with the dataset.","type":"string"},"template_params":{"description":"Table template params.","type":"object"},"time_grain_sqla":{"description":"List of temporal granularities supported by the dataset.","items":{"items":{"type":"string"},"type":"array"},"type":"array"},"type":{"description":"Dataset type.","type":"string"},"uid":{"description":"Dataset unique identifier.","type":"string"},"verbose_map":{"description":"Mapping from raw name to verbose name.","type":"object"}},"type":"object","title":"Dataset"},"schemaType":"response"}