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/get-a-theme.api.mdx

@@ -0,0 +1,68 @@
+---
+id: get-a-theme
+title: "Get a theme"
+description: "Get an item model"
+sidebar_label: "Get a theme"
+hide_title: true
+hide_table_of_contents: true
+api: eJzdWG1v2zYQ/isEsQ8JpsR24GSZin5ws7RN17VF7awD4sClpbOlmiIVknLiCfrvw5GSLdnKS7sBAfbJ5ssd7zk+fHhUTkPQgYpTE0tBffoGDGGCxAYSksgQOPVoyhRLwIDS1L/KaYzzUmYi6lHBEsDWgnpUwU0WKwipb1QGHtVBBAmjfk7NKsVZsTAwB0WLwstpIIUBYXCYpSmPA4YRdL5pDCOvGadKpqBMDBpbgeRZIuxfjFHX3GujYjGnhVd1MKXYCtsLWDUtQGQJ9a+ojuTtpHLp1VNR6+VsCrzWtkYmNhwwAVIAvfYei2HTIaffIDDUo86DT+dgJhjYpIRc4GSb45sM1GqT5BtaXGOWdSqFdtk46nZdUn4ol21w70n4xMWQb7FlFAGp9ZCZVMREQJwRQaND8iXmnEyBGMWE5sxASKYrMsWsUo/CHUtSm4gB+RAHD/mjO2neSSumLmyP01I6DnedbO/w96fA2v8n4Ns8PQ22Ap1x0xJ8xMQcwsl0tTs2i5U2a1wJu3sPYm4i6p/0W7LkErt9ljF7T3ZS1FXiqr5+3c31/YdlFEECn0GbQRofzsEcXmoXRAVTikkI3LBJlCVMxH+DDVoBCz8KvnLShNMV4F78n7PSeyi6WE/0ShtIasNTKTkw0RiehEwtHp0DM1Zyb3caitAkZMbqj8g4Z1OM2V0Ru6qJSNrSdnTc9R43zzIHeCZVwgz1Xcejhg+o83ZqcZXGrbEjCAPCY22InJHNlfH0q6p2ubR4tgPESKJAhKCeLi/DSN6SC1TA38CwmOunicrawb2XRUMbnyDhJSerVVu0t9Vjqy42VO9BAShX7TWI76iwTfWd3orcbqBG5w2GOms3vY6M9Pi4C6f9bvcAjn6dHvR7Yf+A/dI7Oej3T06Oj/v9brfb3WXVVeXnusmJlp20BUOTKXZ8pmRC/rA1XOHR/r8qFRLQms2hhcKP0GZtSF+xkKDMgTY+uRBLxuOQbEpLkiq5jEMI2/DUbB2W3vNiuRQsM5FUSC+fDDITgTDl+mSt5S1A6oYOSf95kXyQhsxkJkKfYCVTJhkw3VpmCg+zBE2ENATuYkz/Lqi1D4vo6Oi59yZVMsDmlAPBfTErn/yJdHP7A0pJ1YbjTGY8tFBLD6U1LnX83MfnQhhQgnGiQS1BORQ+GQiSCbhLIcBNs51EBkGm7iHga2YYX6fAoxqCTCFGfNl9uzXUv7rGZ4Zhc6tC9v7TqEJ3B4EMYWhDcw9BzsSc+jS4/Py+EvJN07EH25ni5OAv8uZ8RMY0Mib1Ox0uA8YjqY1/2j097bA07ix7Haujnd6YkvF4LAg5eEvGdFAeGJtpn7wCpkCRnwZnZ+fD4WT08ffzD2NK8UlZxvNpZSIpahGtO9YxxUkqlanYrsdiLKp3FXm57sb7fg/jIE8O3HPTI2AhKP0y3wp/TH0ypiWEMSU/ExYg0SZGLkAUY7E/FqmKhdmrwjlEau3t79cBvmNLNrR7WgPZ6NwkXwqNONfY2C2LDZmBCSIL7buA5Q10ftUm27uEML9WG5U7iCOL8KuzKPAH4b4YCxciXqnr8LbAl5Mkh0Mu53s4df+FfQwnYCIZuke0/VCBpSJtBp+niwJTYo+NI26mMGOtwOn2gXmPwySEJXCZJiBMeQDthjhHeaqkkYHkhd/p5Oiq8HMkWLHj7SzTRiaVC48umYpRp6pXp3Xjyq2y7LBhYi1XfrIom/hjj2XT/9vR6BNZ+yk8itE0/a3x7gQ3dMqCY1jLEKnIxSd0gliaTlpTVdrb2UWB+1OpyzBwMuKXGpPTqWXH66pOf/dlRMsvRvb9YEc3NaoFjY+JWzNRMFOgox91Yj+uzORudT3MUlAa6sV/rQu54+Ytey4l2iTMin5Z99kvZ8RybjsztXuj9QNbGaCBO9NJOYttaWu5lZecvqIsjTGMXlVuUo/66QIZ4Lb4iub5lGm4VLwosNt9PUK63xvLfUsvYGW/NyE/eYbj9rRVZHVOY3vBhtSfMa7hAcR7n8uCaJ/ct2D1ChKr+ppVIOmCFtfIZas7dnU3MAgCsHpXmezcyQ2ReHOO/MACrP5UrVhS/kHvreHkuZvhhKxYR2elGwMsin8AfSdZMg==
+sidebar_class_name: "get api-method"
+info_path: developer-docs/api/superset
+custom_edit_url: null
+hide_send_button: true
+show_extensions: true
+---
+
+import MethodEndpoint from "@theme/ApiExplorer/MethodEndpoint";
+import ParamsDetails from "@theme/ParamsDetails";
+import RequestSchema from "@theme/RequestSchema";
+import StatusCodes from "@theme/StatusCodes";
+import OperationTabs from "@theme/OperationTabs";
+import TabItem from "@theme/TabItem";
+import Heading from "@theme/Heading";
+import Translate from "@docusaurus/Translate";
+
+<Heading
+  as={"h1"}
+  className={"openapi__heading"}
+  children={"Get a theme"}
+>
+</Heading>
+
+<MethodEndpoint
+  method={"get"}
+  path={"/api/v1/theme/{pk}"}
+  context={"endpoint"}
+>
+
+</MethodEndpoint>
+
+
+
+Get an item model
+
+<Heading
+  id={"request"}
+  as={"h2"}
+  className={"openapi-tabs__heading"}
+>
+  <Translate id="theme.openapi.request.title">Request</Translate>
+</Heading>
+
+<ParamsDetails
+  {...require("./get-a-theme.ParamsDetails.json")}
+>
+
+</ParamsDetails>
+
+<RequestSchema
+  {...require("./get-a-theme.RequestSchema.json")}
+>
+
+</RequestSchema>
+
+<StatusCodes
+  {...require("./get-a-theme.StatusCodes.json")}
+>
+
+</StatusCodes>