docs(cmd): add package docs to CLI and developer tools

cmd/internal-tools/bundle-check/main.go

@@ -1,3 +1,4 @@
+// Command bundle-check is a developer tool that bundles a spec file to confirm it compiles.
 package main
 
 import (

cmd/internal-tools/hier-check/main.go

@@ -1,3 +1,4 @@
+// Command hier-check is a developer tool that parses a hierarchy dump and reports selector matches.
 package main
 
 import (

cmd/sanderling/main.go

@@ -1,3 +1,4 @@
+// Command sanderling is the CLI entry point for the property-based UI fuzzer.
 package main
 
 import (