docs: cut 6.1.0 versions for user_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), broken-internal-
links fix (#40102), and user_docs rename (#40171) all landed. With
the rename in place, all four sections now produce parallel-named
files at the docs/ root (no more bare `versioned_docs/` outlier).

Versioning behavior: lastVersion stays at current for every section,
so the canonical URLs (/user-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.

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:
    user_docs_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.
- developer_docs/extensions/overview.md snapshot has the FIXED
  ./mcp.md form (from #40102), so the SPA-nav 404 isn't baked into
  the 6.1.0 version.

Verified via full yarn build: exit 0, no broken links surfaced by
onBrokenLinks: throw.

docs/developer_docs_versioned_docs/version-6.1.0/api/schemas/chartdataextras.schema.mdx

@@ -0,0 +1,31 @@
+---
+id: chartdataextras
+title: "ChartDataExtras"
+description: ""
+sidebar_label: "ChartDataExtras"
+hide_title: true
+hide_table_of_contents: true
+schema: true
+sample: {"column_order":["string"],"having":"string","instant_time_comparison_range":"string","relative_end":"today","relative_start":"today","time_grain_sqla":"P1D","transpile_to_dialect":true,"where":"string"}
+custom_edit_url: null
+---
+
+import Schema from "@theme/Schema";
+import Heading from "@theme/Heading";
+
+<Heading
+  as={"h1"}
+  className={"openapi__heading"}
+  children={"ChartDataExtras"}
+>
+</Heading>
+
+
+
+
+
+<Schema
+  {...require("./chartdataextras.Schema.json")}
+>
+
+</Schema>