test(core): close package mutation gate

Classify only the two non-terminating const-loop mutations after deterministic fingerprint outputs are asserted, then prove the complete hemx-core package mutation-clean through xtask.

req: abi/003

req: test/020

req: test/021

req: test/022

.cargo/mutants.toml

@@ -3,10 +3,14 @@
 # - test_process_poll_delay: poll cadence is operational; readiness and timeout are integration-proven.
 # - Drop for TestProcess: mutating reaping leaks helper processes beyond the test lifecycle.
 # - inspection_fingerprint: deliberately unobservable test-harness metadata.
+# - BuildFingerprint::from_parts loop-progress mutations: syntactically valid but
+#   non-terminating const-loop mutants; deterministic hash outputs are asserted.
 exclude_re = [
   "test_process_try_wait",
   "test_process_poll_delay",
   "delete statement std::thread::sleep\\(Duration::from_millis\\(25\\)\\)",
   "<impl Drop for TestProcess>::drop",
   "inspection_fingerprint",
+  "replace \\+= with \\*= in BuildFingerprint::from_parts",
+  "replace 1 with 0 in BuildFingerprint::from_parts",
 ]