Add dedicated monero-sys tracing log

[louiss72]

What changed

• Added a dedicated JSON rolling trace layer for monero_sys and monero_cpp.
• The new files use the tracing-monero-sys*.log prefix so wallet-thread/channel-close diagnostics can be inspected without filtering through unrelated wallet/RPC traffic.
• Updated the tracing initialization message to mention both monero wallet and monero-sys trace files.

Why

Issue #695 needs better diagnostics for unexpected monero-sys channel closure. The maintainer asked for monero-sys trace logs in their own file, so this PR isolates the Rust wrapper and C++ callback targets while leaving existing general and wallet logs intact.

Validation

• git diff --check
• rg -n "tracing-monero-sys|MONERO_SYS_CRATES|monero-sys" swap/src/common/tracing_util.rs

I could not run Rust tests locally because this environment still has no cargo or rustfmt available.

Closes #695

[Einliterflasche]

We are not accepting vibe coded PRs. https://github.com/eigenwallet/core/blob/master/AI_POLICY.md