Two initialization methods:

• initialize_fee_vault: Creates a fee vault with a signer keypair
• initialize_fee_vault_pda: Creates a fee vault using PDA for deterministic addresses

Multi-user support: Supports 2-5 users per vault (configurable via MAX_USER constant)

Token compatibility: Supports both SPL Token and Token-2022 standards

Share-based allocation: Each user has a defined share amount that determines their portion of fees

Precision calculations: Uses 52-bit precision scaling for accurate fee distribution math

Dynamic fee accumulation: Tracks fee_per_share to calculate individual user rewards over time

Flexible funding: Anyone can fund fees into the vault via fund_fee instruction

Transfer fee handling: Automatically accounts for token transfer fees (important for Token-2022)

Amount validation: Ensures funded amounts are greater than zero

Real-time distribution: Fees are immediately distributed proportionally to all users

Index-based claiming: Users claim fees using their assigned index (0-4)

Authorization: Only the designated user can claim their fees

Checkpoint system: Tracks fee_per_share_checkpoint to calculate unclaimed rewards

Accumulated tracking: Maintains running total of claimed fees per user

Vault authority: Uses PDA-based authority for secure token operations

Token vault: Dedicated token account for holding fees

Multi-token support: Each vault is tied to a specific token mint

Transfer utilities: Includes helper functions for token transfers

Ownership controls: Each vault has a designated owner

User validation: Validates user addresses and share amounts during initialization

Index bounds checking: Prevents out-of-bounds access to user array

Math overflow protection: Safe math operations throughout

Mint verification: Ensures only supported token mints can be used

Initialization events: Logs vault creation with all parameters

Funding events: Tracks fee funding activities with amounts and funders

Claiming events: Records fee claims with user details and amounts

Zero-copy accounts: Efficient memory usage with zero-copy account structures

Modular design: Well-organized instruction handlers and utilities

Future extensibility: Built-in padding fields for future feature additions