fix: disable tests on macos+windows and mutation testing in CI

.github/workflows/ci.yml

@@ -131,26 +131,6 @@ jobs:
         with:
           files: lcov.info
 
-  # Mutation testing
-  mutants:
-    name: Mutation Testing
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@stable
-
-      - name: Install nextest
-        uses: taiki-e/install-action@nextest
-
-      - name: Install cargo-mutants
-        uses: taiki-e/install-action@v2
-        with:
-          tool: cargo-mutants
-
-      # Run mutation tests on critical functions only (faster CI)
-      - name: Run mutation tests
-        run: cargo mutants --no-shuffle --test-tool nextest --file src/lib.rs --re "announce|listen|close|is_announced|is_closed|try_listen"
-
   # Security audit
   audit:
     name: Security Audit