test: expand golden C-codegen tests from 2 to 8 examples

Add golden tests for: structs, generics, algebraic_enums, enums,
methods, strings. Each test captures the expected C output from the
bootstrap compiler for regression detection.

Also remove leftover 'PARSER FIX V2 ACTIVE' debug print from parser.bux.

tests/golden/structs/src/Main.bux

@@ -0,0 +1,29 @@
+// Structs - Basic struct usage
+import Std::Io::{PrintLine, PrintInt};
+
+
+struct Point {
+    x: int;
+    y: int;
+}
+
+func AddPoints(a: Point, b: Point) -> Point {
+    let result: Point = Point { x: a.x + b.x, y: a.y + b.y };
+    return result;
+}
+
+func Main() -> int {
+    let p1: Point = Point { x: 10, y: 20 };
+    let p2: Point = Point { x: 5, y: 15 };
+    let sum: Point = AddPoints(p1, p2);
+    
+    PrintLine("Point sum:");
+    PrintLine("x = ");
+    PrintInt(sum.x);
+    PrintLine("");
+    PrintLine("y = ");
+    PrintInt(sum.y);
+    PrintLine("");
+    
+    return 0;
+}