refactor(10.2-01): nest framework packages under modules

- Move remaining beach packages and embedded admin assets\n- Rewrite framework, example, build, and gate paths

scripts/check-phase4.sh

@@ -31,6 +31,6 @@ echo "==> hello go test"
 go -C examples/hello test ./...
 
 echo "==> race internal/build phrasebook postcard"
-go test -race ./internal/build ./phrasebook ./postcard
+go test -race ./internal/build ./modules/phrasebook ./modules/postcard
 
 echo "phase4 check passed"