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/containers.ls

@@ -7,7 +7,7 @@ more_codes := [...codes, 'failed' => 500]
 empty_numbers: []i32: []
 empty_codes: [str]i32: []
 optional_numbers: []i32?: nil
-optional_elements: []{i32?}: [nil, 1->|.some]
+optional_elements: []{i32?}: [nil, some 1]
 
 Options :: &{
     name: str: 'default'

test/fixtures/valid/control.ls

@@ -11,7 +11,7 @@ choose_block: (bit, i32, i32) -> i32: @ (condition: bit, when_true: i32, when_fa
 first_positive: []i32 -> i32?: @ values: []i32 {
     for value in values {
         if value > 0 {
-            return value->|.some
+            return some value
         }
     }
     nil

test/fixtures/valid/pipelines.ls

@@ -15,9 +15,9 @@ commented := 'value' # an inline comment preserves continuation
 computed := 1 + 2
 ->to_str
 
-fallible: i32 -> i32 ! Error: @ value: i32 { value! }
+fallible: i32 -> i32 ! Error: @ value: i32 { ok value }
 
 propagate: i32 -> i32 ! Error: @ value: i32 {
     result := {value->fallible}?
-    result!
+    ok result
 }

test/fixtures/valid/standard_signatures.ls

@@ -0,0 +1,19 @@
+use math.{pi, sqrt}
+use math as m
+use random.{Pcg32, pcg32, draw_u32}
+use time.{Duration, TimeError, duration_neg}
+use time as t
+
+circle: f64: pi
+root: f64: 4.0->sqrt
+# Host overloads are selected by the operand, so the literal is typed first.
+nine: f32: 9.0
+qualified_root: f32: nine->m.sqrt
+qualified_pi: f32: m.pi
+
+seed: u64: 42
+generator: Pcg32: seed->pcg32
+draw: u32: generator->draw_u32
+
+negate: Duration => Duration ! TimeError: duration_neg
+qualified_negate: t.Duration => t.Duration ! t.TimeError: t.duration_neg

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
+    }
+}