feat(docs): standalone docs page, Hilfe nav entry, rewritten user guide

- docs route renders without the app shell (own header, back-to-app link,
  theme toggle)
- nav entry renamed to Hilfe (de) / Help (en)
- reference links now case-insensitive (schema/tag slugs)
- handbook rewritten as 17-page user guide with links into the API reference
- release notes v0.8.1 added

artifacts/toolrate/src/i18n/locales/en.json

@@ -12,7 +12,7 @@
     "trash": "Trash",
     "admin": "Admin",
     "redundancy": "Redundancy",
-    "docs": "Docs",
+    "docs": "Help",
     "search": "Search tools…"
   },
   "auth": {
@@ -198,7 +198,18 @@
     "reference": "API reference",
     "referenceIntro": "Generated automatically from the OpenAPI spec — all endpoints and data fields of the current version.",
     "onThisPage": "On this page",
-    "searchPlaceholder": "Search docs…"
+    "searchPlaceholder": "Search docs…",
+    "backToApp": "Back to app",
+    "field": "Field",
+    "type": "Type",
+    "required": "Required",
+    "description": "Description",
+    "status": "Status",
+    "schema": "Schema",
+    "parameter": "Parameter",
+    "noResults": "No results",
+    "fields": "Fields",
+    "fieldHelpHint": "Note: form fields link via the ? icon directly to the respective rows of this table."
   },
   "command": {
     "navigate": "Navigate",