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/invalid/anonymous_without_input.ls

@@ -1 +0,0 @@
-identity :: @ value { value }

test/fixtures/invalid/bang_postfix.ls

@@ -0,0 +1 @@
+value :: @ x: i32 -> i32 ! str { x! }

test/fixtures/invalid/bang_prefix.ls

@@ -0,0 +1 @@
+value :: @ x: str -> i32 ! str { !x }

test/fixtures/invalid/keyword_ok_identifier.ls

@@ -0,0 +1 @@
+ok :: @ value { value }

test/fixtures/invalid/keyword_some_identifier.ls

@@ -0,0 +1 @@
+some := 1

test/fixtures/invalid/legacy_some_constructor.ls

@@ -0,0 +1 @@
+value: i32?: 1->|.some

test/fixtures/invalid/legacy_some_pattern.ls

@@ -0,0 +1 @@
+value :: @ x: i32? { match x { |.some y => y; nil => 0 } }