Issue 23 — mock-amm.swap parameter naming is misleading

[Junman140]

Labels: code-quality, priority:low
Body:

Problem
swap(env, to, amount_in, min_amount_out) uses to for the address that is both paying token_in and receiving token_out. This reads as "recipient only" and will confuse anyone extending it to support swap-and-send-elsewhere.

Proposed fix
Rename to trader (or split into payer/recipient if swap-to-another-address becomes a requirement).

Acceptance criteria

• Parameter renamed, call sites updated
• Doc comment clarifies semantics

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