Support some, ok and err wrappers and untyped function inputs

Track the LScript changes since the grammar was first written:

- some, ok and err are reserved prefix operators and wrapper patterns;
  the old |.some/|.ok/|.err forms and postfix/prefix ! are rejected
- function literal inputs may omit their type annotation, and tuple
  components may omit theirs; an empty typed tuple pattern is now just
  the unit pattern
- migrate fixtures, corpus, queries, CST contract and Rust tests

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

test/fixtures/valid/wrappers.ls

@@ -0,0 +1,24 @@
+present: i32?: some 1
+absent: i32?: nil
+success: i32 ! str: ok 1
+failure: i32 ! str: err 'failed'
+piped: i32?: some 4->double
+grouped: i32?: some {4->double}
+
+double :: @ value { value * 2 }
+describe :: @ (label: str, count) -> str { label }
+
+unwrap_or: i32? -> i32: @ value {
+    match value {
+        some inner => inner
+        nil => 0
+    }
+}
+
+handle: i32 ! str -> i32: @ result {
+    match result {
+        ok value if value > 0 => value
+        ok _ => 0
+        err message => message->length
+    }
+}