Add E2E tests to PSM pallet (Westend AH)

[rockbmb]

Closes #586.

The PSM pallet (polkadot-sdk#11068) is not deployed to any production chain. To run E2E tests against it, a custom PAH runtime was built with the pallet patched in and fed to Chopsticks via the ASSETHUBPOLKADOT_WASM environment variable.

EDIT: the PSM pallet has recently been deployed to WAH; the PR has been changed to use it instead. However, the below instructions are still valid to run PET tests against PAH/KAH (the runtimes branch contains all required changes for PAH; KAH is a matter of replication).

The patched runtime lives in the psm-e2e-runtime branch of the runtimes repository. To reproduce the build:

git clone -b psm-e2e-runtime git@github.com:rockbmb/runtimes.git
cd runtimes
cargo build -p asset-hub-polkadot-runtime --release

Then run:

ASSETHUBPOLKADOT_WASM=target/release/wbuild/asset-hub-polkadot-runtime/asset_hub_polkadot_runtime.compact.compressed.wasm yarn test -t psm

• Core swaps: mint, redeem, roundtrip, minimum amount enforcement
  • mint USDC to pUSD — pUSD received > 0, debt equals mint amount, fee to insurance fund
  • mint then redeem — USDC returned > 0
  • mint below MIN_SWAP fails
• Asset lifecycle: add/remove external assets, fee configuration, ceiling weight assignment
  • addExternalAsset with zero ceiling — mint fails
  • addExternalAsset then setCeiling — mint succeeds
  • zero debt then removeExternalAsset — asset is None
  • set custom fee, remove, re-add — fee resets to default
  • mint creates debt, removeExternalAsset blocked — asset still present
  • setMintingFee before adding asset — 3% fee applied on mint
• Circuit breaker: MintingDisabled, AllDisabled, governance origin checks
  • MintingDisabled — mint fails, redeem succeeds
  • AllDisabled — both mint and redeem fail
  • MintingDisabled — debt unchanged, redeem reduces debt
  • signed setMintingFee without root fails
• Value conservation: fee distribution to insurance fund, residual debt from fees
  • set 1% fees, mint and redeem all — insurance fund gain > 0
  • set 1% mint fee, mint 1000, redeem all pUSD — residual debt > 0
  • Bob redeems more than reserve — ExtrinsicFailed
  • fee 0% mint vs fee 5% mint — higher fee yields less pUSD
• Ceiling dynamics: global debt ceiling, per-asset weight normalization, zero-weight blocking
  • mint 500, setMaxPsmDebt(1) blocks mint, restore allows mint
  • setMaxPsmDebt(10_000), fund USDT, mint USDC and USDT — total debt > 0
  • setAssetCeilingWeight(USDT, 0) — mint USDC succeeds, debt equals amount
  • setAssetCeilingWeight(USDC, 0) — mint fails despite AllEnabled circuit breaker
  • both assets at 75% weight — normalized to 50/50, enforced at boundary
  • setMaxPsmDebt(0) after minting both assets — mints blocked, redeems work
  • mint 500, zero maxPsmDebt — debt unchanged, mint blocked, redeem reduces debt
• Reserve integrity: over-redemption rejection, multi-account behavior, debt accumulation
  • setMaxPsmDebt(5_000), mint 200 — debt > 0
  • mint 500, give Bob 2x debt pUSD, Bob redeems debt plus MIN_SWAP — ExtrinsicFailed
  • mint 500 then mint 200 more — debt > 500 UNIT
  • mint 500, redeem MIN_SWAP — Redeemed event
• rebase psm-e2e-runtime branch onto main now that polkadot-sdk#11068 has been merged; verify that the extra scaffolding added to the PAH runtime still compiles and is compatible with the latest runtimes release
• create assetHubWestend.psm.e2e.test.ts, and test PSM on WAH

[rockbmb]

Concerning (and unrelated) failure in bifrostKusama.basilisk.xcm (88296838829683); I'll investigate this locally.