Vendor Cordis framework packages as source

cordis 4.0.0-rc.6, plugin-loader, -include, -group, -timer, -hmr,
-logger-console, cosmokit 1.8.1, schemastery 3.18.0 — copied from the
cordis-workspace checkout, flattened under vendor/, original npm names,
private: true. vendor/README.md is the manifest: upstream repos +
commit SHAs, local-modification log, sync procedure.

Local modification: hmr's locale YAML imports and .i18n() call removed
(avoids a runtime YAML import hook we don't vendor).

vendor/group/tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "lib"
+  },
+  "include": ["src"],
+  "references": [
+    { "path": "../cordis" },
+    { "path": "../loader" }
+  ]
+}