Fuse Avail Light Client with Real-time NFT ownership (resilient nft verification)

NFT Verification Improvements Summary:

Added initial NFT check requirement

Created a new initial_nft_check() function that must succeed for the client to start
Prevents client from running without valid NFT verification
Implemented robust retry mechanism

Added tracking of consecutive failures (counter resets on success)
Set maximum consecutive failures to 12 (allowing for 1 hour of downtime)
Used fixed 5-minute retry intervals between attempts
Added timeout handling

Implemented 30-second timeout for NFT verification requests
Prevents client from hanging indefinitely on network issues
Improved error handling

Immediate shutdown for NFT validation failures (Ok(false))
Graceful retries for network/connection errors
Clear shutdown after max retries (30 min)
Enhanced logging

Added detailed logs showing retry attempt counts
Clear messaging about retry intervals
Explicit shutdown reason messages
Maintained security requirements

Still enforces NFT validation requirement
No compromise on security while improving resilience
These changes make the Light Client much more resilient to temporary monitoring service outages while still enforcing the NFT validation requirement when appropriate.