Add performance and management fees

[jribbink]

Closes #30

Adds management and performance fees to FCMVault. Off by default (rates 0, recipient unset); the admin configures them post-deploy via setters.

Mechanics

• Management — NAV × bps × Δt / year (billable gap clamped at one year, so a long dormancy can't catch-up-bill more than the annual rate).
• Performance — bps × (gain in WETH-per-share above a strict, flow-neutral high-water mark). WETH-denominated, so the HWM excludes WETH price beta and charges only the strategy's carry; no charge in drawdown, no double-charge. Crystallizes on unrealized, oracle-marked NAV — bounded by the strict all-time HWM, the 50% cap, and dilution (not asset outflow).
• Collected by minting shares to feeRecipient (dilution) — no assets leave the vault, so collection never triggers an unwind/swap.
• Accrual — _accrueFees() runs at the top of deposit/redeem/redeemInKind/rebalance, plus a permissionless accrueFees(). Accrues Morpho interest first; advances the clock + HWM unconditionally so fees meter from when they're enabled, never retroactively.
• Caps — MAX_MANAGEMENT_FEE_BPS 10% / MAX_PERFORMANCE_FEE_BPS 50%; setters (DEFAULT_ADMIN_ROLE) revert above them and accrue at the old rate first.