Clean repo root: remove 140 build artifacts, dead code, stale scripts

Deleted: 31 .log files, 50+ Conan cmake artifacts, archive/ (legacy code),
benchmark/, temp/ (test snippets), stress-test-logs/, doge_testnet/,
build-qt/, build-qt-mvp/, build-release/, stale shell scripts.
Root went from 164 items to 24.

Author: frstrtr