Feat/stash dex

[lastperson]

Closes: #244

[Copilot]

Pull request overview

This PR introduces a new upgradeable StashDex contract intended to provide a stash-backed swap interface (borrow tokenOut from configured liquidity pools, route tokenIn to a configured processor, and enforce an oracle-validated fee), along with deployment/config updates and comprehensive tests.

Changes:

• Adds the StashDex upgradeable contract with per-route fee config, borrowing via ILiquidityPool.borrowDirect, repay/forward flows, and a proxied balance() view for indexers.
• Adds a full Hardhat test suite for StashDex behavior (routes, pools, fees, pause, repay/forward, and proxy deployment).
• Adds deployment + network config plumbing for StashDex and extends the liquidity pool interface/testing mocks (directDebt).

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
contracts/StashDex.sol	New upgradeable DEX contract that borrows from liquidity pools and routes tokenIn to processors.
contracts/interfaces/ILiquidityPool.sol	Adds directDebt() to the pool interface.
contracts/testing/TestLiquidityPool.sol	Enhances test pool to track/repay direct debt.
contracts/testing/TestWETH.sol	Adds mint() helper for tests.
test/StashDex.ts	Comprehensive StashDex test coverage (proxy init, routes/pools, swap, repay/forward, pause, balance).
scripts/deployStashDex.ts	New deployment script for StashDex proxy + initial config.
scripts/helpers.ts	Adds default Hardhat network config for StashDex.
scripts/test.ts	Includes StashDex deploy in the script-based test deploy flow.
network.config.ts	Adds StashDex config shape + initial ETHEREUM StashDex config and proxy IDs used by scripts.
coverage-baseline.json	Updates baseline coverage numbers.

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