Fix clang-tidy warnings in script parser and tokenizer

- Add explicit != 0 for implicit int->bool conversions from ctype
  functions (readability-implicit-bool-conversion)
- Value-initialize op variables in switch statements
  (cppcoreguidelines-init-variables)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: facontidavide

src/script_parser.cpp

@@ -304,7 +304,7 @@ class ScriptParser
   Ast::expr_ptr parseAssignment(Ast::expr_ptr left)
   {
     const auto& opTok = advance();
-    Ast::ExprAssignment::op_t op;
+    Ast::ExprAssignment::op_t op{};
     switch(opTok.type)
     {
       case TokenType::ColonEqual:
@@ -382,7 +382,7 @@ class ScriptParser
   static Ast::expr_ptr makeBinary(Ast::expr_ptr left, TokenType opType,
                                   Ast::expr_ptr right)
   {
-    Ast::ExprBinaryArithmetic::op_t op;
+    Ast::ExprBinaryArithmetic::op_t op{};
     switch(opType)
     {
       case TokenType::Plus:

src/script_tokenizer.cpp

@@ -22,22 +22,22 @@ namespace
 
 bool isIdentStart(char c)
 {
-  return std::isalpha(static_cast<unsigned char>(c)) || c == '_' || c == '@';
+  return std::isalpha(static_cast<unsigned char>(c)) != 0 || c == '_' || c == '@';
 }
 
 bool isIdentChar(char c)
 {
-  return std::isalnum(static_cast<unsigned char>(c)) || c == '_';
+  return std::isalnum(static_cast<unsigned char>(c)) != 0 || c == '_';
 }
 
 bool isDigit(char c)
 {
-  return std::isdigit(static_cast<unsigned char>(c));
+  return std::isdigit(static_cast<unsigned char>(c)) != 0;
 }
 
 bool isHexDigit(char c)
 {
-  return std::isxdigit(static_cast<unsigned char>(c));
+  return std::isxdigit(static_cast<unsigned char>(c)) != 0;
 }
 
 }  // namespace