refactor: update Show implementation for Char to use new syntax and improve output handling

[bobzhang]

Error: Moonc.Basic_hash_string.Key_not_found("$@moonbitlang/core/builtin.Show::Char::to_string")

[peter-jerry-ye-code-review]

Consolidation of intrinsic function implementation

Category
Maintainability
Code Snippet
pub impl Show for Char with to_string(self) = "%char.to_string"
Recommendation
The change is good, but consider adding a comment explaining that this is an intrinsic function implementation
Reasoning
While the new syntax is more concise, it's less immediately clear that this is an intrinsic function. A brief comment would help future maintainers understand the implementation without having to look up the syntax.

Documentation could be more descriptive

Category
Maintainability
Code Snippet
///| Convert Char to String
Recommendation
Enhance the documentation to: ///| Converts a Char to its String representation using the intrinsic implementation
Reasoning
The current documentation is very basic. Since this is a core conversion functionality, having more detailed documentation would be helpful for users of the library.

Removal of explicit implementation might affect behavior

Category
Correctness
Code Snippet

• fn char_to_string(char : Char) -> String {
• [char]
• }
  Recommendation
  Verify that the intrinsic %char.to_string produces identical results to the previous implementation of converting a char to a single-character array
  Reasoning
  The old implementation explicitly showed the conversion logic (creating a single-character array). We should ensure the intrinsic function maintains the same behavior.