refactor: reuse fee helper when hydrating pending swaps

[victortran0904]

Summary

• use apply_fee_deduction(..., FEE_DIVISOR) when hydrating user_receives from an on-chain reservation
• add regression coverage for a non-divisible destination amount

Fixes #334

Tests

• uv run pytest tests/test_probe_pending_reservation.py -q
• uv run pytest tests/test_rate.py -q
• uv run ruff check allways/cli/swap_commands/helpers.py tests/test_probe_pending_reservation.py
• git diff --check

[Copilot]

Pull request overview

This PR removes duplicated protocol-fee math in the CLI pending-swap hydration path by reusing the shared apply_fee_deduction helper, and adds a regression test to ensure fee rounding behavior stays correct for non-divisible destination amounts.

Changes:

• Refactor hydrate_pending_swap to compute user_receives via apply_fee_deduction(state.to_amount, FEE_DIVISOR) instead of inlining the calculation.
• Add a regression test covering fee deduction when to_amount is not cleanly divisible by the fee divisor (e.g., 101 -> 100).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
allways/cli/swap_commands/helpers.py	Replaces inline fee deduction with the shared apply_fee_deduction helper using FEE_DIVISOR.
tests/test_probe_pending_reservation.py	Adds regression coverage verifying hydrate_pending_swap sets fee-adjusted user_receives for non-divisible amounts.

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