[pallet-revive] Fix storage deposit refunds in nested contract calls

[0xRVE]

fixes paritytech/contract-issues#213 where storage deposit refunds failed in nested/reentrant calls.

Problem
Storage refunds were calculated incorrectly when a contract allocated storage, then performed a nested call that cleared it. Pending storage changes lived only in the parent FrameMeter, so child frames could not see them and refunds were skipped.

Solution
Apply pending storage deposit changes to a cloned ContractInfo before creating nested frames. This makes the parent’s storage state visible to child frames during refund calculation.

Implementation

• Added apply_pending_changes_to_contract() to apply pending diffs to ContractInfo
• Added apply_pending_storage_changes() wrapper on FrameMeter
• Applied pending storage changes before nested frame creation in exec.rs (3 locations)

[0xRVE]

/cmd prdoc --audience runtime_dev --bump patch

[pgherveou]

can you capture the example from the issue in the tests?

[0xRVE]

can you capture the example from the issue in the tests?

nested_call_refund_matches_direct_refund asserts that a nested clear refunds the same as a direct clear. If you have a different reproducer in mind, please point me to the exact steps and I will mirror it in the tests.

[paritytech-workflow-stopper]

All GitHub workflows were cancelled due to failure one of the required jobs.
Failed workflow url: https://github.com/paritytech/polkadot-sdk/actions/runs/21477444021
Failed job name: fmt