feat: reimplement the analysis stack in Rust

[brenorb]

Summary

• add a Rust workspace with a spec-driven core domain, analysis engine, and detector pack
• add a direct Bitcoin Core RPC adapter that reads backend/script/config.ini instead of shelling out per request
• add CLI and Axum HTTP adapters that preserve the report contract used by the existing frontend

Testing

• cargo test
• cargo run -p stealth-app --bin stealth-app -- --help
• cargo run -p stealth-app --bin stealth-api -- --help

Notes

• live regtest acceptance against the existing setup.sh / reproduce.py harness is not automated in this PR yet