Add cargo-mutants cronjob

Author: shinghim

.cargo/mutants.toml

@@ -0,0 +1 @@
+examine_globs = ["units/src/*.rs"]

.github/workflows/cron-weekly-cargo-mutants.yml

@@ -0,0 +1,19 @@
+name: Weekly cargo-mutants
+on:
+  schedule:
+    - cron: "0 0 * * 0" # runs weekly on Sunday at 00:00
+  workflow_dispatch: # allows manual triggering
+jobs:
+  cargo-mutants:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: taiki-e/install-action@v2
+        with:
+          tool: cargo-mutants
+      - run: cargo mutants -vV --in-place
+      - uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: mutants-out
+          path: mutants.out

.gitignore

@@ -14,6 +14,7 @@ hashes/target
 
 # Test artifacts
 bitcoin/dep_test
+mutants.out*
 
 # Fuzz artifacts
 hfuzz_target