Implement Code Frames for Compiler Errors

[eugenioenko]

Description:
Currently, compiler errors (scanning and parsing) only show line and column numbers. To improve debugging, we should display a small snippet of the source code (a "code frame") with a pointer to the exact location of the
error.

Example Output:

   1   3 | <div>{{ 1 + }}</div>
   2     |             ^

Tasks:

• Add source?: string to KasperError constructor.
• Implement a generateCodeFrame utility in src/types/error.ts.
• Update Scanner, Parser, and TemplateParser to pass the original source string when throwing errors.
• Only show code frames in development mode.