ci: исполнять TS/Python parity на чистом runner (#548)

Issue: #548
User-Visible: no

scripts/mutation-gate.mjs

@@ -3202,6 +3202,19 @@ const MUTANT_DEFINITIONS = [
         + '`${point[0].toFixed(6)},${point[1].toFixed(6)}`;',
     }],
   },
+  {
+    id: 'junction-limit-ts-python-parity-drift',
+    guard: 'npx tsc -p tsconfig.junction-parity.json && node scripts/fix-test-build.mjs '
+      + '&& python3 tests_backend/junction_parity.py --build-dir=test-build/junction-parity',
+    because: 'the clean-runner parity job must turn red when either production mirror changes '
+      + 'one shared rule; otherwise a green run can again mean that no cross-runtime comparison '
+      + 'actually happened (#548 AC2)',
+    patches: [{
+      file: 'src/junction-limits.ts',
+      find: 'export const MIN_NODE_DISTANCE_CM = 5;',
+      replace: 'export const MIN_NODE_DISTANCE_CM = 4; // mutant: drift from Python mirror',
+    }],
+  },
   {
     id: 'junction-limit-branch-dropped',
     guard: 'npx tsc -p tsconfig.test.json && node scripts/fix-test-build.mjs '