[Feature]: Add .addNote() method to ErrorInstance #9

Feature Description

Implement the .addNote() method on the ErrorInstance type. This method enriches errors with additional context notes, inspired by Python 3.11's add_note() functionality.

Problem It Solves

• Errors often need additional context discovered at runtime
• Notes provide better debugging information without changing the core API
• Enables rich error enrichment after catching

Proposed Solution

import { error, raise } from '@deessejs/errors';

const AppError = error({ name: 'AppError' });

try {
  processData(input);
} catch (err) {
  raise(AppError().addNote('Processing failed at line 42'));
}

// Multiple notes supported
raise(
  AppError()
    .addNote('Attempt 1 failed')
    .addNote('Retrying...')
    .addNote('Attempt 2 failed')
);

Alternatives Considered

• Type guards approach (deferred to v1.2.0)
• Context injection via withContext() (deferred to v2.0.0)