feat: implement startup mode and improved peer discovery

- Add startup mode with faster timings for initial peer discovery
- Implement early exit from startup mode when enough streams found
- Add network-specific peer discovery limits and validation
- Improve advertise() function with better error handling and logging
- Add isValidPeer() stub for future peer validation logic
- Use configurable DHT request limits instead of hardcoded values
- Add target valid peer counting and filtering
- Improve advertiseLoop() with adaptive timing based on discovery success

Author: GheisMohammadi