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/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"}