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/versioned_docs/version-6.1.0/databases/supported/google-bigquery.mdx

@@ -0,0 +1,31 @@
+---
+title: Google BigQuery
+sidebar_label: Google BigQuery
+description: "Google BigQuery is a serverless, highly scalable data warehouse."
+hide_title: true
+---
+
+{/*
+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 { DatabasePage } from '@site/src/components/databases';
+
+export const databaseInfo = {"engine":"google_bigquery","engine_name":"Google BigQuery","module":"bigquery","documentation":{"description":"Google BigQuery is a serverless, highly scalable data warehouse.","logo":"google-big-query.svg","homepage_url":"https://cloud.google.com/bigquery/","categories":["CLOUD_GCP","ANALYTICAL_DATABASES","PROPRIETARY"],"pypi_packages":["sqlalchemy-bigquery"],"connection_string":"bigquery://{project_id}","install_instructions":"echo \"sqlalchemy-bigquery\" >> ./docker/requirements-local.txt","authentication_methods":[{"name":"Service Account JSON","description":"Upload service account credentials JSON or paste in Secure Extra","secure_extra":{"credentials_info":{"type":"service_account","project_id":"...","private_key_id":"...","private_key":"...","client_email":"...","client_id":"...","auth_uri":"...","token_uri":"..."}}}],"notes":"Create a Service Account via GCP console with access to BigQuery datasets. For CSV/Excel uploads, also install pandas_gbq.","warnings":["Google BigQuery Python SDK is not compatible with gevent. Use a worker type other than gevent when deploying with gunicorn."],"docs_url":"https://github.com/googleapis/python-bigquery-sqlalchemy","custom_errors":[{"regex_name":"CONNECTION_DATABASE_PERMISSIONS_REGEX","message_template":"Unable to connect. Verify that the following roles are set on the service account: \"BigQuery Data Viewer\", \"BigQuery Metadata Viewer\", \"BigQuery Job User\" and the following permissions are set \"bigquery.readsessions.create\", \"bigquery.readsessions.getData\"","error_type":"CONNECTION_DATABASE_PERMISSIONS_ERROR","category":"Permissions","description":"Insufficient permissions","issue_codes":[1017]},{"regex_name":"TABLE_DOES_NOT_EXIST_REGEX","message_template":"The table \"%(table)s\" does not exist. A valid table must be used to run this query.","error_type":"TABLE_DOES_NOT_EXIST_ERROR","category":"Query","description":"Table not found","issue_codes":[1003,1005]},{"regex_name":"COLUMN_DOES_NOT_EXIST_REGEX","message_template":"We can't seem to resolve column \"%(column)s\" at line %(location)s.","error_type":"COLUMN_DOES_NOT_EXIST_ERROR","category":"Query","description":"Column not found","issue_codes":[1003,1004]},{"regex_name":"SCHEMA_DOES_NOT_EXIST_REGEX","message_template":"The schema \"%(schema)s\" does not exist. A valid schema must be used to run this query.","error_type":"SCHEMA_DOES_NOT_EXIST_ERROR","category":"Query","description":"Schema not found","issue_codes":[1003,1016]},{"regex_name":"SYNTAX_ERROR_REGEX","message_template":"Please check your query for syntax errors at or near \"%(syntax_error)s\". Then, try running your query again.","error_type":"SYNTAX_ERROR","category":"Query","description":"SQL syntax error","issue_codes":[1030]}]},"time_grains":{"SECOND":true,"FIVE_SECONDS":false,"THIRTY_SECONDS":false,"MINUTE":true,"FIVE_MINUTES":true,"TEN_MINUTES":true,"FIFTEEN_MINUTES":true,"THIRTY_MINUTES":true,"HALF_HOUR":false,"HOUR":true,"SIX_HOURS":false,"DAY":true,"WEEK":true,"WEEK_STARTING_SUNDAY":false,"WEEK_STARTING_MONDAY":true,"WEEK_ENDING_SATURDAY":false,"WEEK_ENDING_SUNDAY":false,"MONTH":true,"QUARTER":true,"QUARTER_YEAR":false,"YEAR":true},"score":83,"max_score":201,"joins":true,"subqueries":true,"supports_dynamic_schema":false,"supports_catalog":true,"supports_dynamic_catalog":true,"ssh_tunneling":false,"supports_file_upload":true,"query_cancelation":false,"query_cost_estimation":true,"sql_validation":false,"user_impersonation":false};
+
+<DatabasePage name="Google BigQuery" database={databaseInfo} />