docs: add wiki, complete lib nav, and rebuild mcp artifacts

- Add hand-written wiki (index, overview, how-to, extending, dev) with
  MkDocs config following the platform anatomy
- Complete the library nav by registering the csv and xlsx groups in
  docforge.nav.yml and docs/mkdocs.lib.yml
- Regenerate lib/MCP outputs with the rebuilt nav

docs/mcp/index.json

@@ -1,5 +1,5 @@
 {
-  "project": "omniread",
+  "project": "OmniRead",
   "type": "docforge-model",
   "modules_count": 22,
   "source": "docforge"