feat: Implement DoS protection for bulk contract operations

[kryputh]

Overview

This PR addresses Issue #238 by implementing robust protection against Denial of Service (DoS) attacks targeting bulk operations. It introduces batch size constraints, gas budget monitoring, and per-caller rate limiting across all critical modules.

Changes

• bulk_limits.rs: New module defining MAX_BATCH_SIZE, MAX_GAS_BUDGET, and rate-limiting logic.
• Bridge: Limited validator signature counts and added rate limiting to bridge_out.
• Emergency: Limited the number of chains that can be paused/resumed in a single transaction.
• Message Passing: Added gas budget checks to check_timeouts to prevent iteration-based DoS.
• Tokenization: Capped the number of tags allowed during NFT minting and updates.
• Escrow: Limited the number of signers permitted for new escrows.
• Reporting & BFT: Integrated gas guards into all loops that iterate over stored maps (validators, proposals, report templates, etc.).

Verification

• Verified code structure and logic flow across all modified modules.
• Implemented unit tests within bulk_limits.rs for batch checking and rate-limit reset logic.

Closes #238

[Xhristin3]

@kryputh resolve conflicts.

[kryputh]

Sure I will do that soon