fix: fix critical audit from ag

[Lchangliang]

1. Prevention of Liveness and Panic Vulnerabilities (Consensus)

Delayed QC Aggregation Panic Fix (pending_votes.rs): Replaced a panic! with graceful error handling (VoteReceptionResult::ErrorAddingVote) when a delayed Quorum Certificate (QC) aggregation is triggered with insufficient voting power. This prevents the consensus from crashing upon receiving stale or maliciously delayed votes.
Rotating Proposer Safety (rotating_proposer_election.rs): Added strict assertions during RotatingProposer initialization to guarantee that the proposer set is not empty and contiguous_rounds > 0, neutralizing potential division-by-zero or out-of-bounds panics.
2. Prevention of Undefined Behavior (UB) in Concurrency (gravity_node)

Safe Environment Variables (

main.rs
): Moved the conditional evaluation and mutation of RUST_BACKTRACE to the absolute start of

main()
before any threads are spawned. This mitigates a known Undefined Behavior (UB) caused by calling std::env::set_var in a multithreaded environment.
3. Data Recovery and State Sync Improvements (api/bootstrap.rs & api/consensus_mempool_handler.rs)

Optimized Block Buffer Initialization: Completely refactored the recovery exit condition during init_block_buffer_manager. Instead of an ad-hoc flag, the loop now intelligently breaks once the block_number_to_block_id map length fulfills the required range

(latest_block_number - start_block_number + 1)
, significantly improving boot/sync performance.
Unhandled Channel Logs: Added explicit .is_none() error logging internally if the persist_notifiers channel silently closes during commit_blocks or commit_ledger, averting silent transaction processing failures.
Save Transaction Robustness: Properly handled the

Err
result returned by self.inner.db.writer.save_transactions(...) during the commit_ledger sequence, actively logging any database storage faults.
4. Block Parent Resolution Safety (block_buffer_manager.rs)

Integer Underflow Protection: Safeguarded the block parent lookup mechanism by using checked_sub(1). When evaluating block_number == 0 (the genesis block edge-case), it skips looking up parent mappings and inherently relies on the canonically provided parent_id, averting subtraction underflow crashes.