Fix high-priority issues: concurrency safety, naming consistency, and…

[y001j]

… error handling

This commit addresses three critical issues identified in the code review:

1. Fix concurrent safety issue with global variable 'increase'

   • Changed from plain uint64 to atomic.Uint64
   • Use atomic.Add(1) for thread-safe ID generation
   • Removed unnecessary panic recovery code

2. Fix package naming inconsistency in example/echoserver.go

   • Changed all 'UringNet' references to 'uringnet' (lowercase)
   • Ensures consistent package naming throughout the codebase

3. Add comprehensive error handling

   • Added new error types: ErrSocketCreation, ErrInvalidSocketFd, ErrRingSetup, ErrFileRegister
   • Updated New() function with proper error checking
   • Updated NewMany() function with proper error handling and validation
   • Updated SetLoops() to return error and validate inputs
   • Added error handling to echoserver example with usage instructions
   • Improved error messages with context using fmt.Errorf with %w

These changes improve code reliability, maintainability, and user experience.