Add client redirects for the seven doc URLs the upgrade moves

Docusaurus treats a doc whose filename matches its folder as that
category's index page, a convention introduced after 2.0.0-beta.5.
Upgrading therefore shortens seven API doc URLs, e.g.

    /docs/mapillary.config/mapillary.config -> /docs/mapillary.config

Nothing in the repo references the old paths and every internal link
regenerates, but external bookmarks and inbound links would 404. This
adds @docusaurus/plugin-client-redirects and maps each old path to its
new one.

Verified by building and following each redirect: all seven stubs are
emitted with the correct target, and the content reached through them
matches what the old URL served. The only differences are chrome the
v3 theme renders differently (prev/next arrows, dark-mode toggle icons).

Build output goes 43 -> 50 pages: 43 real pages plus 7 redirect stubs.
Internal link check still reports 0 unresolvable across 49 links.

docs/tags is intentionally not redirected. It existed in v2 as an empty
tag index with no tags to list; v3 omits it rather than emitting an
empty page.

Author: caglarpir

docs/docusaurus.config.js

@@ -150,6 +150,29 @@ module.exports = {
       copyright: `Copyright © ${new Date().getFullYear()} Facebook, Inc. Built with Docusaurus.`,
     },
   },
+  plugins: [
+    [
+      '@docusaurus/plugin-client-redirects',
+      {
+        // Docusaurus treats a doc whose filename matches its folder as that
+        // category's index page, a convention introduced after 2.0.0-beta.5.
+        // Upgrading therefore shortened these seven URLs. Redirect the old
+        // paths so external links and bookmarks keep working.
+        redirects: [
+          'mapillary',
+          'mapillary.config',
+          'mapillary.config.api',
+          'mapillary.controller',
+          'mapillary.models',
+          'mapillary.models.api',
+          'mapillary.utils',
+        ].map((name) => ({
+          from: `/docs/${name}/${name}`,
+          to: `/docs/${name}`,
+        })),
+      },
+    ],
+  ],
   presets: [
     [
       '@docusaurus/preset-classic',

docs/package.json

@@ -19,6 +19,7 @@
   },
   "dependencies": {
     "@docusaurus/core": "^3.10.2",
+    "@docusaurus/plugin-client-redirects": "^3.10.2",
     "@docusaurus/preset-classic": "^3.10.2",
     "@mdx-js/react": "^3.0.0",
     "clsx": "^2.1.1",

docs/yarn.lock

@@ -1694,6 +1694,21 @@
     react-helmet-async "npm:@slorber/react-helmet-async@1.3.0"
     react-loadable "npm:@docusaurus/react-loadable@6.0.0"
 
+"@docusaurus/plugin-client-redirects@^3.10.2":
+  version "3.10.2"
+  resolved "https://registry.yarnpkg.com/@docusaurus/plugin-client-redirects/-/plugin-client-redirects-3.10.2.tgz#55023f8538baf7e66ec33c49ab65879c74fd93cd"
+  integrity sha512-z5I5ttCXw+8y2gHVZvqAMmUw4Rb0ZzKA5eCPk87SfM/jCKOTvE24yDpPAwwipvug96ij7mOwEHXWw8G4LlWdGA==
+  dependencies:
+    "@docusaurus/core" "3.10.2"
+    "@docusaurus/logger" "3.10.2"
+    "@docusaurus/utils" "3.10.2"
+    "@docusaurus/utils-common" "3.10.2"
+    "@docusaurus/utils-validation" "3.10.2"
+    eta "^2.2.0"
+    fs-extra "^11.1.1"
+    lodash "^4.17.21"
+    tslib "^2.6.0"
+
 "@docusaurus/plugin-content-blog@3.10.2":
   version "3.10.2"
   resolved "https://registry.yarnpkg.com/@docusaurus/plugin-content-blog/-/plugin-content-blog-3.10.2.tgz#2374886ec3d76e8f014e85db8c3c010de6c419be"