ludic.base: core_undrained fills a list the caller keeps; hd_refuse's panic declared; ludic.photo's slug declared (a photograph taken)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.base/handle.ludic

@@ -34,6 +34,7 @@ export function hd_new(p: HandlePool) -> int {
   return s | (p.gen[s] << 22)
 }
 
+@alloc_ok("only when a pool is full: the words of its panic")
 function hd_refuse(p: HandlePool) -> int {
   p.refused += 1
   if p.strict { panic(`handle pool {p.name} is full at {len(p.gen)}`) }