feat: add modifiers with validation and access control to LiquidityManagerV2

[SynnekOG]

Pull Request

Summary

This PR introduces a set of reusable modifiers in LiquidityManagerV2 to enforce stricter validation, access control, and safety checks across liquidity management functions.

Changes

• Section Header
  • Added Modifiers section with NatSpec header for clarity and organization.
• New Modifiers
  • onlyFactory: restricts function calls to the factory contract.
  • validTokenPair: ensures both token addresses are valid and distinct.
  • onlySupportedTokens: restricts operations to supported token pairs.
  • validAmount: checks that provided amounts are greater than zero.
  • deadlineCheck: enforces deadlines to mitigate stale transactions.
• Formatting
  • Applied forge fmt for consistent code style.

Motivation

Modifiers reduce code duplication and make function-level validation more readable and maintainable.
They ensure:

• Security: Unauthorized callers or invalid token pairs are blocked early.
• Robustness: Prevents accidental zero amounts or expired transactions.
• Clarity: Clearly expresses preconditions for function execution.

Next Steps

• Apply these modifiers to liquidity-related functions (addLiquidity, removeLiquidity, initializePool, etc.).
• Expand modifiers as needed for role-based permissions and protocol safety guarantees.