feat(docs): mkdocs-style documentation site served at /docs

Full documentation hub replacing the release-notes-only view:
- Handbook pages (docs/handbook) for all features and admin/betrieb
- API reference generated from lib/api-spec/openapi.yaml via
  scripts/src/generate-docs.mjs (replaces sync-release-docs.mjs):
  endpoints, schemas/fields, search index, per-release snapshots
- mkdocs layout: sidebar nav, right TOC with scrollspy, search overlay,
  version dropdown, repo link
- FieldHelp (?) buttons in forms linking to reference field docs
- v0.7.0 release notes backfilled, v0.8.0 release notes added

artifacts/toolrate/src/index.css

@@ -265,6 +265,25 @@
  */
 @layer utilities {
 
+  /* Documentation heading anchors (mkdocs style "¶" links) */
+  .docs-prose :is(h1, h2, h3, h4) {
+    scroll-margin-top: 6rem;
+    position: relative;
+  }
+
+  .docs-prose .docs-anchor::after {
+    content: "¶";
+    margin-left: 0.35rem;
+    font-size: 0.8em;
+    color: hsl(var(--muted-foreground));
+    opacity: 0;
+    transition: opacity 0.15s ease;
+  }
+
+  .docs-prose :is(h1, h2, h3, h4):hover .docs-anchor::after {
+    opacity: 0.8;
+  }
+
   /* Hide ugly search cancel button in Chrome until we can style it properly */
   input[type="search"]::-webkit-search-cancel-button {
     @apply hidden;