Add a Global HTTP Exception Filter That Returns a Consistent JSON Error Shape Across All Endpoints

[mftee]

Description:
Add a standalone global HTTP exception filter that returns consistent, structured error responses across the entire API.

Tasks:

• Create src/common/filters/http-exception.filter.ts implementing ExceptionFilter
• Catch all HttpException and generic Error instances
• Return a uniform JSON shape: { statusCode, message, error, timestamp, path }
• Register the filter globally in main.ts
• Map unhandled Error instances to 500 Internal Server Error without leaking stack traces in production (NODE_ENV=production)

Acceptance Criteria:

• All API error responses follow the defined JSON shape
• Stack traces are hidden in production but logged server-side
• Validation errors from the global ValidationPipe are also formatted by this filter