fix(stableswap)!: fix peg ordering by accepting and co-sorting asset-peg pairs

[khuzama98]

Description

Fixes a peg-ordering bug in create_pool_with_pegs where passing assets and peg
sources in different orders caused silent misalignment after internal sorting.

Root cause: do_create_pool sorted assets internally, but the corresponding
peg_source array was not co-sorted — so peg_source[i] could end up paired with
the wrong asset after sort.

Changes:

• Breaking: create_pool_with_pegs now accepts BoundedVec<(AssetId, PegSource), _>
  instead of separate assets and peg_source parameters. Pairing is now explicit at
  the call site, making misalignment impossible.
• Assets and peg sources are co-sorted by asset ID before pool creation; do_create_pool
  no longer sorts internally (callers are now responsible for providing sorted assets).
• create_pool (non-peg variant) sorts assets at dispatch.
• Added debug_assert! in get_target_pegs verifying assets arrive pre-sorted.

Related Issue

Fixes: #1164

Motivation and Context

A pool created via create_pool_with_pegs with assets provided in non-ascending order
would store a peg source at an index that no longer matched its intended asset after the
internal sort. This caused incorrect peg values to be applied to assets, a correctness
issue with direct impact on pool pricing.

How Has This Been Tested?

• added peg-ordering unit tests to 3-asset pools with generic test helpers
  (pallets/stableswap/src/tests/peg_ordering.rs)
• Updated all affected unit test suites: peg.rs, peg_one.rs, peg_ordering.rs,
  pegs_with_different_decimals.rs, update_peg_source.rs, update_max_peg_update.rs,
  remove_liquidity.rs
• Added integration regression test in integration-tests/src/stableswap.rs that
  creates a pool with out-of-order assets and asserts correct peg assignment post-sort

Checklist:

• I have updated the documentation if necessary.
• I have added tests to cover my changes, regression test if fixing an issue.
• This is a breaking change.

[github-actions]

Crate versions that have been updated:

• runtime-integration-tests: v1.78.0 -> v1.78.1
• pallet-hsm: v1.7.0 -> v1.7.1
• pallet-stableswap: v7.3.0 -> v8.0.0
• hydradx-runtime: v410.0.0 -> v411.0.0

Runtime version has been increased.

[Copilot]

Pull request overview

Fixes a correctness bug in the Stableswap pallet where assets were internally sorted during pool creation but peg sources were not co-sorted, causing silent peg/asset misalignment and incorrect pricing.

Changes:

• Breaking API change: create_pool_with_pegs now takes explicit (asset_id, peg_source) pairs and co-sorts them by asset_id before storage.
• Moves/clarifies sorting responsibility: create_pool sorts assets at dispatch; do_create_pool no longer sorts internally and expects pre-sorted assets.
• Adds/updates extensive unit + integration regression coverage for peg ordering, and bumps versions accordingly.

Reviewed changes

Copilot reviewed 22 out of 23 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
runtime/hydradx/src/lib.rs	Bumps runtime spec_version to reflect the breaking change.
runtime/hydradx/Cargo.toml	Bumps runtime crate version.
pallets/stableswap/src/lib.rs	Changes peg-pool creation API to asset/peg pairs, co-sorts pairs, removes internal sorting in do_create_pool, and adds a sorted-assets debug assertion for peg resolution.
pallets/stableswap/src/benchmarks.rs	Updates benchmarks to call create_pool_with_pegs using (asset, peg) pairs.
pallets/stableswap/README.md	Updates documentation to describe (asset_id, peg_source) pairing and sorting semantics.
pallets/stableswap/Cargo.toml	Major version bump for the breaking pallet API.
pallets/stableswap/src/tests/mod.rs	Registers new peg_ordering test module.
pallets/stableswap/src/tests/mock.rs	Updates test ExtBuilder to construct (asset, peg) pairs when creating peg pools.
pallets/stableswap/src/tests/peg.rs	Updates tests to the new peg-pool creation signature.
pallets/stableswap/src/tests/peg_one.rs	Updates tests to the new peg-pool creation signature.
pallets/stableswap/src/tests/peg_ordering.rs	Adds dedicated regression tests ensuring peg sources are co-sorted with assets and pricing behavior matches sorted-reference pools.
pallets/stableswap/src/tests/pegs_with_different_decimals.rs	Updates tests to the new peg-pool creation signature.
pallets/stableswap/src/tests/remove_liquidity.rs	Updates tests to the new peg-pool creation signature.
pallets/stableswap/src/tests/update_peg_source.rs	Updates tests to the new peg-pool creation signature.
pallets/stableswap/src/tests/update_max_peg_update.rs	Updates tests to the new peg-pool creation signature.
pallets/hsm/src/tests/mock.rs	Updates HSM test ExtBuilder to call create_pool_with_pegs using (asset, peg) pairs.
pallets/hsm/src/benchmarks.rs	Updates HSM benchmarks to call create_pool_with_pegs using (asset, peg) pairs.
pallets/hsm/Cargo.toml	Patch bump reflecting dependent breaking change adaptation.
integration-tests/src/stableswap.rs	Updates existing peg-pool creation usage and adds an integration regression test for reversed-order asset inputs.
integration-tests/src/omnipool_liquidity_mining.rs	Updates peg-pool creation usage to the new signature.
integration-tests/src/hsm.rs	Updates peg-pool creation usage to the new signature.
integration-tests/Cargo.toml	Patch bump for integration tests crate.
Cargo.lock	Updates lockfile versions for the bumped crates.

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