fix: vendor per-kind sites in the hub; drop stale blog docs

- collect.py: when a kind points at the shared site root, copy only the
  per-kind subdir (site/lib -> <repo>/lib) instead of the whole site, so
  stray single-site build output never leaks into the hub
- Purge stale collected artifacts (404.html, assets/, search/, sitemaps,
  objects.inv, duplicate mcp/) from every repo dir, matching the cleaned
  source site/ roots
- Refresh collected output from source repos, incl. the khata-app app
- Remove the vendored Blog API docs (config.yml entry + blog/) and its card

openapi-first/mcp/modules/openapi_first.templates.vet_app.sse.json

@@ -1,44 +0,0 @@
-{
-  "module": "openapi_first.templates.vet_app.sse",
-  "content": {
-    "path": "openapi_first.templates.vet_app.sse",
-    "docstring": null,
-    "objects": {
-      "asyncio": {
-        "name": "asyncio",
-        "kind": "alias",
-        "path": "openapi_first.templates.vet_app.sse.asyncio",
-        "signature": "<bound method Alias.signature of Alias('asyncio', 'asyncio')>",
-        "docstring": null
-      },
-      "random": {
-        "name": "random",
-        "kind": "alias",
-        "path": "openapi_first.templates.vet_app.sse.random",
-        "signature": "<bound method Alias.signature of Alias('random', 'random')>",
-        "docstring": null
-      },
-      "json": {
-        "name": "json",
-        "kind": "alias",
-        "path": "openapi_first.templates.vet_app.sse.json",
-        "signature": "<bound method Alias.signature of Alias('json', 'json')>",
-        "docstring": null
-      },
-      "subscribe": {
-        "name": "subscribe",
-        "kind": "function",
-        "path": "openapi_first.templates.vet_app.sse.subscribe",
-        "signature": "<bound method Function.signature of Function('subscribe', 33, 37)>",
-        "docstring": null
-      },
-      "unsubscribe": {
-        "name": "unsubscribe",
-        "kind": "function",
-        "path": "openapi_first.templates.vet_app.sse.unsubscribe",
-        "signature": "<bound method Function.signature of Function('unsubscribe', 40, 48)>",
-        "docstring": null
-      }
-    }
-  }
-}