feat: leverage looping for borrowers

[starksama]

Summary

One-click leverage looping for borrowers. User picks a target leverage (e.g. 2.5x), Monarch builds the full position automatically.

Context

Real user request from an institutional user:

"I choose my effective leverage (ie 250%) and then you build the position. It's a pain in the ass to do this manually rn, so time consuming. Especially with a wallet that requires institutional approvals."

Flow

1. User selects a Morpho market
2. User inputs collateral amount and target effective leverage (e.g. 2.5x)
3. Monarch calculates the loop: supply collateral → borrow → swap → supply more → repeat
4. Execute in a single transaction via bundler / multicall
5. Display final position: effective leverage, health factor, liquidation price

Requirements

• Leverage calculator: given base amount + target leverage, compute loop iterations and final amounts
• Transaction builder: batch supply/borrow/swap steps via Morpho bundler
• UI: leverage slider or input with real-time position preview (health factor, liquidation price, net APY)
• Safety: cap max leverage based on LLTV, warn on high-risk positions
• Unwind: support deleveraging (repay → withdraw collateral → swap → repay more)

Related

• #NEW — Auto-mint ERC-4626 vault shares as collateral (separate feature for markets where collateral is a vault token)
• Similar to Contango-style looping
• Morpho bundler supports multicall for batched operations