feat(lang): 0.S - a reference out of a read-only state is read-only (named so), a program's type named like the runtime's is refused (PadButton), tests for both, the migrate case covers lets; changeset

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

examples/rejected/module_let_alias.ludic

@@ -0,0 +1,9 @@
+# 0.S: a module-level let is immutable all the way down, through a local that holds it too
+program ModuleLetAlias {
+  let LIMITS: []int = [1, 2]
+  entry {
+    let l = LIMITS
+    push(l, 3)
+    print(len(LIMITS))
+  }
+}

examples/rejected/runtime_type_clash.ludic

@@ -0,0 +1,10 @@
+# a program's type named like one the runtime declares is refused (it compiled, and the two layouts
+# met in the IR): the runtime's input has `enum PadButton`
+program RuntimeTypeClash {
+  property PadButton { code: int = 0 }
+  entry {
+    let b = new PadButton
+    print(b.code)
+    print(Input.pad_button(0, 1))
+  }
+}

examples/rejected/state_alias_readonly.ludic

@@ -0,0 +1,13 @@
+# 0.S: a reference read out of a read-only state is read-only too
+program StateAliasReadonly {
+  property Row { n: int = 0 }
+  state Table { rows: []Row = new []Row }
+  function bump(t: Table) -> void {
+    let r = t.rows[0]
+    r.n = 1
+  }
+  entry (t: mut Table) {
+    push(t.rows, new Row)
+    bump(t)
+  }
+}