fence (25.1c/25.2): natives by library in the census, and @alloc_ok's allocations declared at run time

The census reads ludic.physics' jph_heap_bytes/_peak and the Vulkan runtime's lvk_ac_bytes/_peak by
name (dlsym, so nothing a package declares is declared twice) and prints jolt, vulkan and the rest
of the heap apart. An @alloc_ok function counts a scope in and out (@lp_fdecl): what it and its
callees make is marked declared in the side table, reported as 'declared' in the census and left
out of a frame's verdict and of Mem.kept().

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

selfhost/backend/emit_decl.ludic

@@ -32,10 +32,13 @@ function emit_fn(d: Node) -> void {
     loc_push(p.s, slot, p.ty)
     i += 1
   }
+  let declared = fr_alloc_ok(d.s)                # 25.1: what an @alloc_ok function makes, callees too, is declared
+  if declared { emit("  %decl.in = atomicrmw add ptr @lp_fdecl, i32 1 monotonic\n") }
   emit_block(d.a)
   if not (rl == "void") and not block_ends(d.a) { perr(`function '{d.s}' can reach its end without returning a {ret_ty}`) }
   if not g_term { emit("  br label %ret\n") }
   emit("ret:\n")
+  if declared { emit("  %decl.out = atomicrmw sub ptr @lp_fdecl, i32 1 monotonic\n") }
   if (rl == "void") { emit("  ret void\n") }
   else { let r = emit_bind(`load {rl}, ptr %retval`);  emit("  ret ");  emit(rl);  emit(" ");  emit(r);  emit("\n") }
   code = saved