wip(0.S1, 0.S2): state records, mut and read-only state parameters, entry injection, module var refused; ludic migrate state

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

examples/rejected/module_let_write.ludic

@@ -0,0 +1,8 @@
+# 0.S: a module-level let is immutable all the way down - a write through it is refused
+program ModuleLetWrite {
+  let LIMITS: []int = [1, 2]
+  entry {
+    LIMITS[0] = 3
+    print(LIMITS[0])
+  }
+}