Return compact peer list by default when `compact` param is absent (BEP 23)

[josecelano]

Goal

Fix the HTTP tracker announce handler to return the compact peer list by default when the client omits the compact GET parameter, aligning the tracker with the SUGGESTION in BEP 23.

Background

BEP 23 states: "It is SUGGESTED that trackers return compact format by default." The current implementation only returns compact when compact=1 is explicit. When absent, it falls through to non-compact (dictionary) format.

Scope

• Invert the compact-default logic in build_response so None maps to compact
• Remove the deviation NOTICE in packages/axum-http-server/src/lib.rs
• Rename and invert the contract test
• Remove the code-review comment that flagged this deviation

Full spec: docs/issues/drafts/align-http-tracker-compact-default-with-bep-23/ISSUE.md