Build a basic Bollinger Bands Uniswap v4 hook contract AND update the existing GoldenCrossHook.sol.

=== PART A: NEW FILE — BollingerHook.sol ===

SPEC:

• Contract name: BollingerHook.sol
• Location: contracts/BollingerHook.sol (same repo as GoldenCrossHook.sol)
• Indicator: Bollinger Bands, 20-period SMA, 2 standard deviations
• Rebalance logic: When price crosses upper band (SMA + 2σ) → rebalance toward lower. When price crosses lower band (SMA - 2σ) → rebalance toward upper.
• Keep it standalone. No multi-signal logic. No EWMA. No custom math beyond standard Bollinger calculation.
• Must compile with: Hardhat 2.26.3, @uniswap/v4-core 1.0.2, @uniswap/v4-periphery 1.0.3, OpenZeppelin 5.0.2
• PoolManager: 0x8366a39cc670b4001a1121b8f6a443e40951
• Chain: Robinhood Chain (chainId 4663)
• Follow the same contract structure/patterns as GoldenCrossHook.sol in this repo (hooks, fee handling, pool config)
• Include a SwapBollinger.sol library for the math (SMA + stddev calculation)
• Must compile green: npx hardhat compile
• Do NOT add governance, ratchet, or phase-flip logic. Those are in GovernancePool.sol already.
• Constructor should accept: PoolManager address, gas wallet, accumulator, treasury, creator wallet, charity router (6 addresses)
• Fee: 45 bps (25 flywheel + 17 creator + 3 charity router)

DELIVERABLE:

• contracts/BollingerHook.sol
• contracts/libraries/SwapBollinger.sol
• Both compile clean against existing hardhat.config.js

=== PART B: MODIFY — GoldenCrossHook.sol ===

SPEC:

• Add address charityRouter_ as the 6th constructor parameter
• Add it to the revert ZeroAddress() check (same pattern as the other 5)
• Add it to the revert InvalidRecipient() check (same pattern as the other 5)
• Store as public address charityRouter;
• Update the fee split logic: change creator fee from 20 bps to 17 bps, add 3 bps routed to charityRouter
• Total remains 45 bps (25 flywheel + 17 creator + 3 charity router)
• Do NOT change any other logic (SMA calculation, rebalance trigger, BaseHook inheritance)
• Must still compile green: npx hardhat compile

DELIVERABLE:

• Updated contracts/GoldenCrossHook.sol (6-param constructor, 25/17/3 split)
• Compiles clean

=== BOTH PARTS ===

• Push all changes to repo
• Confirm npx hardhat compile passes with all hook files present