Add npm backfill pipeline, shared htpasswd registry auth docs

- drone npm template gains backfill-npm-from-tags (mirrors PyPI)
- document the shared /auth/htpasswd credential model (npm + PyPI +
  docker) and Verdaccio's bcrypt requirement
- point doc-weaver source/path at ../react/doc-weaver

standards/mcp/repos.json

@@ -38,7 +38,7 @@
     {
       "name": "doc-weaver",
       "type": "package",
-      "path": "doc-weaver",
+      "path": "react/doc-weaver",
       "version_source": "package.json",
       "drone": "npm-lib.yaml",
       "trigger": "tag",