feat(lang): packages count under uses; a port of defaults may go unbound

A module that says uses must name every package module it reaches; a
package with no module line is named for its directory (ludic_render3d)
for this rule, so a mechanic reaching into the renderer is caught. Only
the engine's runtime needs no naming. 'module x uses' with nothing after
it reaches no other module. A port whose every member has a default
answers with its defaults when unbound, and 'new' of a port says to bind
it. ludic-dev test runs 'ludic test packages'. Reseed.

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

examples/rejected/uses_pkg_mech/index.ludic

@@ -0,0 +1,8 @@
+# uses_pkg_mech/index.ludic - a mechanic that says it uses ludic_base, then reaches into another
+# mechanic package
+module mech uses ludic_base
+import "ludic.base"
+import "ludic.inventory"
+export function stock() -> int {
+  return inv_count(0)
+}