refactor(certgen): drop dead native logging code

Remove orphaned native logging that nothing reached:

- The /sdcard/Download zip dump (NativeCertGen.dump and the dumpLogs
  JNI, dump_logs_inner, dump.rs, pub mod dump), superseded by the
  diag.sh export.
- The verbose-marker helpers (sysfs.rs, pub mod sysfs); the manual
  .verbose toggle still works via mod.rs::init's inline check.

Drop the now-unused direct deps zip and libc and the orphaned jstring
import. cargo ndk build is warning-clean.

native-certgen/Cargo.toml

@@ -20,8 +20,6 @@ time = { version = "0.3", features = ["std"] }
 anyhow = "1.0"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
-libc = "0.2"
-zip = { version = "2.2", default-features = false, features = ["deflate"] }
 serde_json = "1.0"
 
 [profile.release]