- cache/lru.rs: replace lock().unwrap() with if let Ok guard,
consistent with other lock acquisitions in the same file
- service/repo/core.rs: replace try_into().unwrap() with
copy_from_slice which is infallible for fixed-size slices
- service/auth/rsa.rs: replace 3 expect() calls with map_err()
for ChaCha20Poly1305 key init and session key retrieval
- config/mod.rs: replace GLOBAL_CONFIG.get().expect() with
unwrap_or_else fallback to empty config
zhenyi