feat(lang): L5 generic records and functions

property Pool<T> { ... }, function first<T>(xs: []T) -> T, map<T, U> over fn
types; a type writes an instance as Pool<Thing>, nested as deep as needed. The
parser names an instance Pool$Thing and remembers its generic and arguments; the
checker takes the generic declarations out, infers a call's type arguments from
its arguments or its result's declared slot, and makes each instance once as an
ordinary record or function, checked like any other. Errors print Pool<Thing>.
An instance keeps its generic's module and export (L3). ludic-fmt keeps type
arguments together while spacing comparisons and shifts.

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

examples/rejected/generic_unbound.ludic

@@ -0,0 +1,9 @@
+# L5: a call whose type arguments nothing decides is refused - give the result a declared type
+program GenericUnbound {
+  property Pool<T> { n: int = 0 }
+  function pool_new<T>() -> Pool<T> { return new Pool<T> }
+  entry {
+    let p = pool_new()
+    print(p.n)
+  }
+}