Language: match statement

match state {
        Title => { if button.start { state = Playing } }
        Playing => { /* ... */ }
        GameOver => { if button.a { state = Title } }
        _ => {}
    }

- Lexer: \`match\` keyword and \`=>\` (FatArrow) token
- Parser: \`parse_match\` after the existing loop constructs. Each
  arm is \`pattern => { body }\`, with \`_\` as the catch-all. The
  match scrutinee is parsed with struct-literal restriction enabled
  so the following \`{\` is unambiguously the match body, not a
  struct literal.
- The parser desugars match directly into an if/else-if chain so
  the analyzer, IR lowering, and codegen don't need new AST variants
  — each arm becomes \`scrutinee == pattern\` as the condition, and
  the default arm (if any) becomes the final \`else\` block.

Tests cover parse + full pipeline integration for state-style
dispatch using an enum.

https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3

tests/integration_test.rs

@@ -228,6 +228,36 @@ fn program_with_for_loop() {
     rom::validate_ines(&rom_data).expect("should be valid iNES");
 }
 
+#[test]
+fn program_with_match_statement() {
+    // Note: the parser doesn't support `;` as a statement separator,
+    // so each arm body uses newlines between statements.
+    let source = r#"
+        game "Match" { mapper: NROM }
+        enum Mode { Idle, Run, Jump }
+        var mode: u8 = Idle
+        var x: u8 = 0
+        on frame {
+            match mode {
+                Idle => { if button.a { mode = Run } }
+                Run => {
+                    x += 1
+                    if button.b { mode = Jump }
+                }
+                Jump => {
+                    x += 2
+                    if button.a { mode = Idle }
+                }
+                _ => {}
+            }
+            wait_frame
+        }
+        start Main
+    "#;
+    let rom_data = compile(source);
+    rom::validate_ines(&rom_data).expect("should be valid iNES");
+}
+
 #[test]
 fn program_with_struct_literals() {
     let source = r#"