feat: list each declared doc kind as its own homepage card

- compute per-kind home URLs (lib/, api/, wiki/) via _find_home_for_kind
- emit one card per declared kind so multi-kind repos (e.g. doc-forge
  with lib + wiki) appear in each matching homepage section
- declare the doc-forge wiki kind and refresh its vendored site with the
  combined lib + wiki build

doc-forge/mcp/index.json

@@ -1,6 +1,6 @@
 {
   "project": "docforge",
   "type": "docforge-model",
-  "modules_count": 22,
+  "modules_count": 23,
   "source": "docforge"
 }