SI-7: Review tests and align v1 namespace across REST API packages

[josecelano]

Subissue of EPIC #1938 — REST API Contract-First Migration

Problem

During the contract-first migration (SI-1 through SI-5), production code was moved from axum-rest-api-server to the new layered packages (rest-api-protocol, rest-api-application, rest-api-runtime-adapter). However, two issues remain:

1. Tests left in wrong package: The file axum-rest-api-server/src/v1/context/torrent/resources/torrent.rs contains unit tests for conversion functions that now live in rest-api-runtime-adapter::conversion. These tests should be moved alongside their production code.

2. Inconsistent v1 namespace: Packages rest-api-application and rest-api-runtime-adapter expose their modules at the top level, while rest-api-protocol, axum-rest-api-server, and rest-api-client use a v1/ module. The two outlier packages should be aligned.

Scope

Part A: Move misplaced tests

• Move conversion tests from axum-rest-api-server/src/v1/context/torrent/resources/torrent.rs to rest-api-runtime-adapter::conversion.
• Remove empty stub axum-rest-api-server/src/v1/context/torrent/resources/peer.rs and its module declaration.

Part B: Align v1 namespace

• Add v1/ module to rest-api-application and move ports/ and use_cases/ under it.
• Add v1/ module to rest-api-runtime-adapter and move adapters/, container.rs, conversion.rs under it.
• Update all internal imports across the workspace.

Checklist

• Conversion tests moved to rest-api-runtime-adapter
• Empty peer.rs stub removed
• rest-api-application has v1/ module with ports + use-cases
• rest-api-runtime-adapter has v1/ module with adapters + container + conversion
• All internal imports updated
• Workspace builds cleanly
• Pre-commit and pre-push checks pass