DRBalancerVault contract for system DR rebalancing (#269)

* Implement a vault that holds underlying (AMPL) and perp (SPOT) tokens and auto-rebalances to maintain the system's target deviation ratio via IRolloverVault swaps.

Key features:
- Deposit underlying tokens and mint vault notes (LP tokens)
- Redeem notes for proportional underlying + perp tokens
- Auto-rebalance when system DR is outside equilibrium zone:
    DR < 1 (perpTVL too high): redeem perps to decrease perpTVL
    DR > 1 (perpTVL too low): mint perps to increase perpTVL
- Rebalance formula: requiredChange = perpTVL × |dr - targetDR|
  (rolloverVaultTVL unchanged during flash mint/redeem)
- Liquidity limits based on swap direction:
    underlying->perp: limited by underlying balance
    perp->underlying: limited by perp value held
- Separate lag factors and percentage limits for each direction
- Slippage protection with configurable max swap fee percentage
- Keeper-controlled pause functionality.

* Update DRBalancerVault deposit/redeem to accept both tokens with slippage protection

- Update deposit() to accept both underlying and perp tokens with signature:
  deposit(underlyingAmtMax, perpAmtMax, minNotesMinted)
- Update redeem() to include slippage protection with signature:
  redeem(notesAmt, minUnderlyingAmtOut, minPerpAmtOut)
- Update computeMintAmt() to return (notesMinted, underlyingAmtIn, perpAmtIn)
- First deposit accepts any ratio; subsequent deposits enforce vault ratio
- Update Deposited event to include perpAmtIn
- Fix lag factor comments (swapped DR conditions)
- Add InvalidLagFactor validation to prevent division by zero
- Update contract docstring to reflect dual-token deposits

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* renamed events

* added dr eq range back

* allowing empty equilibriumDR

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: aalavandhan

.gitignore

@@ -23,3 +23,6 @@ artifacts
 #Generated files
 RolloverBatch.json
 RedeemBatch.json
+
+.claude
+CLAUDE.md

spot-contracts/package.json

@@ -26,7 +26,7 @@
     "@ethersproject/providers": "^5.6.8",
     "@nomicfoundation/hardhat-chai-matchers": "latest",
     "@nomicfoundation/hardhat-ethers": "^3.0.0",
-    "@nomicfoundation/hardhat-verify": "latest",
+    "@nomicfoundation/hardhat-verify": "^2.0.0",
     "@nomiclabs/hardhat-waffle": "^2.0.6",
     "@openzeppelin/hardhat-upgrades": "^3.0.4",
     "@openzeppelin/upgrades-core": "latest",