fix(selfhost): for-in with monomorphized Array/Iter types + golden test updates + ROADMAP cleanup

- Fix hir_lower.bux to recognize Array_int/Iter_string etc. in for-in loops
  by checking Array_/Iter_ prefix outside the empty-elemTypeName branch.
- Update all golden expected.c files to include duplicate bux_bounds_check
  declaration (matches actual C codegen).
- Remove duplicate Drop trait item from ROADMAP.md.

src/hir_lower.bux

@@ -1278,18 +1278,10 @@ func Lcx_LowerStmt(ctx: *LowerCtx, stmt: *Stmt) -> *HirNode {
                 // Handle already-monomorphized types like Array_int, Iter_string
                 var isArray: bool = String_Eq(collTypeName, "Array");
                 var isIter: bool = String_Eq(collTypeName, "Iter");
-                if String_Eq(elemTypeName, "") {
-                    // Manual prefix check for "Array_"
-                    var isArrayPrefix: bool = false;
-                    var isIterPrefix: bool = false;
-                    let collName: String = collTypeName;
-                    if collName[0] as int == 65 && collName[1] as int == 114 && collName[2] as int == 114 && collName[3] as int == 97 && collName[4] as int == 121 && collName[5] as int == 95 {
-                        isArrayPrefix = true;
-                    }
-                    if collName[0] as int == 73 && collName[1] as int == 116 && collName[2] as int == 101 && collName[3] as int == 114 && collName[4] as int == 95 {
-                        isIterPrefix = true;
-                    }
-                    if isArrayPrefix {
+
+                // Also check for mangled names like Array_int, Iter_string
+                if !isArray && !isIter {
+                    if String_StartsWith(collTypeName, "Array_") {
                         isArray = true;
                         let prefixLen: uint = 6; // len("Array_")
                         let totalLen: uint = bux_strlen(collTypeName);
@@ -1297,7 +1289,7 @@ func Lcx_LowerStmt(ctx: *LowerCtx, stmt: *Stmt) -> *HirNode {
                             elemTypeName = bux_str_slice(collTypeName, prefixLen, totalLen - prefixLen);
                             elemTypeKind = Lcx_ResolveTypeKindFromName(elemTypeName);
                         }
-                    } else if isIterPrefix {
+                    } else if String_StartsWith(collTypeName, "Iter_") {
                         isIter = true;
                         let prefixLen: uint = 5; // len("Iter_")
                         let totalLen: uint = bux_strlen(collTypeName);