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/src/index.ts

@@ -0,0 +1,3 @@
+import { Group } from '@cordisjs/plugin-loader'
+
+export default Group