Improve Error Handling and Reporting

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# Improve Error Handling and Reporting

## Issue Description
The current error handling in the interpreter is basic and sometimes unhelpful. When errors occur during parsing or execution, the messages can be cryptic or lack sufficient context for debugging.

## Current Limitations
1. Error messages don't always include the line number where the error occurred
2. Some runtime errors result in generic exceptions
3. Syntax errors may not clearly indicate what was expected
4. The interpreter sometimes crashes on certain errors instead of gracefully handling them

## Expected Behavior
- Clear error messages with line and column information
- Specific error types for different categories of errors
- Suggestions for how to fix common errors
- Recovery from errors in interactive mode without crashing

## Technical Details
The error handling system should be enhanced to:
1. Maintain more context during parsing/execution
2. Use specific exception types for different error categories
3. Format error messages with more information
4. Handle errors properly in interactive mode

## Proposed Solution
1. Create a structured Error class with different types and severity levels
2. Enhance the parser to provide better context in error messages
3. Improve the interpreter's exception handling
4. Add recovery mechanisms for interactive mode errors
5. Consider adding a debug mode with more verbose error information

## Related Components
- src/core/parser.cpp - Parsing errors
- src/core/interpreter.cpp - Runtime errors
- src/main.cpp - Error reporting to the user

## Priority
Medium - This improves user experience but doesn't block core functionality

Start by reading src/core/parser.cpp, src/core/interpreter.cpp, and src/main.cpp to trace how parsing, runtime, and interactive-mode errors currently flow. Compare the existing behavior with the requested structured errors, contextual messages, and recovery requirements. Done should include the relevant error categories, line and column context, improved reporting, and graceful interactive-mode handling.

Written by the indexing model from the issue text.