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/annotationlayer.Schema.json

@@ -0,0 +1 @@
+{"schema":{"properties":{"annotationType":{"description":"Type of annotation layer","enum":["FORMULA","INTERVAL","EVENT","TIME_SERIES"],"type":"string"},"color":{"description":"Layer color","nullable":true,"type":"string"},"descriptionColumns":{"description":"Columns to use as the description. If none are provided, all will be shown.","items":{"type":"string"},"type":"array"},"hideLine":{"description":"Should line be hidden. Only applies to line annotations","nullable":true,"type":"boolean"},"intervalEndColumn":{"description":"Column containing end of interval. Only applies to interval layers","nullable":true,"type":"string"},"name":{"description":"Name of layer","type":"string"},"opacity":{"description":"Opacity of layer","enum":["","opacityLow","opacityMedium","opacityHigh",null],"nullable":true,"type":"string"},"overrides":{"additionalProperties":{"nullable":true},"description":"which properties should be overridable","nullable":true,"type":"object"},"show":{"description":"Should the layer be shown","type":"boolean"},"showLabel":{"description":"Should the label always be shown","nullable":true,"type":"boolean"},"showMarkers":{"description":"Should markers be shown. Only applies to line annotations.","type":"boolean"},"sourceType":{"description":"Type of source for annotation data","enum":["","line","NATIVE","table"],"type":"string"},"style":{"description":"Line style. Only applies to time-series annotations","enum":["dashed","dotted","solid","longDashed"],"type":"string"},"timeColumn":{"description":"Column with event date or interval start date","nullable":true,"type":"string"},"titleColumn":{"description":"Column with title","nullable":true,"type":"string"},"value":{"description":"For formula annotations, this contains the formula. For other types, this is the primary key of the source object."},"width":{"description":"Width of annotation line","minimum":0,"type":"number"}},"required":["name","show","showMarkers","value"],"type":"object","title":"AnnotationLayer"},"schemaType":"response"}