feat(docs): version-based docs, correct Gitea tag links, form guide help

- each release now carries a full docs snapshot (reference + handbook)
  under docs/releases/<v>/; the docs frontend loads a version's snapshot
  for /docs/vX.Y.Z/* and shows the handbook/reference of that version
- version dropdown navigates to /docs/<version> (docs home) instead of
  the release notes page; old /docs/vX.Y.Z redirect removed
- generator: --snapshot writes handbook + reference; build copies
  versioned snapshots (last 7 versions) into /docs/versions/<v>/
- fix Gitea tag links: /admin/tool-evaluator/tags/<v> was 404, correct
  URL is /releases/tag/<v>
- add GuideHelp button to forms/pages linking to the matching handbook
  guide (rating, tool add/edit, costs, compare, watchlist, analytics)

docs/releases/v0.8.2/handbook/index.json

@@ -0,0 +1,104 @@
+[
+  {
+    "slug": "index",
+    "file": "index.md",
+    "title": "Überblick",
+    "order": 1
+  },
+  {
+    "slug": "getting-started",
+    "file": "getting-started.md",
+    "title": "Erste Schritte",
+    "order": 2
+  },
+  {
+    "slug": "konto",
+    "file": "konto.md",
+    "title": "Anmelden & Konto",
+    "order": 3
+  },
+  {
+    "slug": "tools-finden",
+    "file": "tools-finden.md",
+    "title": "Tools finden & durchsuchen",
+    "order": 4
+  },
+  {
+    "slug": "tool-anlegen",
+    "file": "tool-anlegen.md",
+    "title": "Tool anlegen",
+    "order": 5
+  },
+  {
+    "slug": "tool-bearbeiten",
+    "file": "tool-bearbeiten.md",
+    "title": "Tool bearbeiten & löschen",
+    "order": 6
+  },
+  {
+    "slug": "bewerten",
+    "file": "bewerten.md",
+    "title": "Bewerten",
+    "order": 7
+  },
+  {
+    "slug": "watchlist",
+    "file": "watchlist.md",
+    "title": "Watchlist",
+    "order": 8
+  },
+  {
+    "slug": "vergleichen",
+    "file": "vergleichen.md",
+    "title": "Vergleichen",
+    "order": 9
+  },
+  {
+    "slug": "analytics",
+    "file": "analytics.md",
+    "title": "Analytics",
+    "order": 10
+  },
+  {
+    "slug": "plaene",
+    "file": "plaene.md",
+    "title": "Pläne & Berechtigungen",
+    "order": 11
+  },
+  {
+    "slug": "kosten",
+    "file": "kosten.md",
+    "title": "Kosten erfassen",
+    "order": 12
+  },
+  {
+    "slug": "administration",
+    "file": "administration.md",
+    "title": "Administration",
+    "order": 13
+  },
+  {
+    "slug": "redundanz",
+    "file": "redundanz.md",
+    "title": "Redundanz-Dashboard",
+    "order": 14
+  },
+  {
+    "slug": "papierkorb",
+    "file": "papierkorb.md",
+    "title": "Papierkorb",
+    "order": 15
+  },
+  {
+    "slug": "tastatur",
+    "file": "tastatur.md",
+    "title": "Tastenkürzel & Kommandopalette",
+    "order": 16
+  },
+  {
+    "slug": "datenmodell",
+    "file": "datenmodell.md",
+    "title": "Datenmodell",
+    "order": 17
+  }
+]