Bump MGC@69bdf11 + adjust overcapacity test to actually exercise storm

- nodes/machineGroupControl@69bdf11 makes DOWNSTREAM single-writer
  (handlePressureChange = live aggregate; optimizer target moved to
  AT_EQUIPMENT). Closes the ps-mgc-flow-contract failure.

- test/inflow-overcapacity-stability now starts the basin at maxLevel
  so PS percControl is immediately 100 % (the actual storm condition)
  and uses real-time waits between ticks so movementManager intervals
  fire — the previous setImmediate yield was too fast for moves to
  progress, making pumps look perma-parked even when behaviour was OK.
  Park observations dropped from 83 to 3 across the sim window; final
  ctrl converges to ~88 % across all 3 pumps.

All 82 cross-node + node integration tests now pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

test/inflow-overcapacity-stability.integration.test.js

@@ -22,7 +22,11 @@ test('inflow ≫ capacity: pumps reach steady high-ctrl, no parking, no thrashin
   // wall time while still exercising the transient (1 s startup + 2 s
   // warmup). The race conditions we care about are the same — they're
   // about ORDER, not absolute duration.
-  const plant = buildPlant({ initialBasinLevel: 2.6 });
+  // Start at maxLevel so PS percControl is immediately 100 % (the
+  // storm condition). Otherwise the basin needs to fill to maxLevel
+  // first, which on a 2× capacity inflow takes ~2 minutes — longer
+  // than this test's wall time.
+  const plant = buildPlant({ initialBasinLevel: 3.5 });
   const { ps, mgc, pumps, advance, restore } = plant;
   try {
     // Pre-start pumps to operational so the test focuses on STEADY-STATE
@@ -39,8 +43,14 @@ test('inflow ≫ capacity: pumps reach steady high-ctrl, no parking, no thrashin
     let abortLogObservations = 0;
 
     // Drive the loop: every tick, refresh pressures, set inflow,
-    // tick PS (which fires _applyMachineGroupLevelControl).
+    // tick PS (which fires _applyMachineGroupLevelControl). The
+    // settlePerTickMs wait is REAL wall-clock so movementManager's
+    // setInterval timers actually fire between handleInputs — without
+    // it the test runs too fast for moves to progress and pumps look
+    // permanently parked even when production behaviour is fine.
     const ticks = SIM_SECONDS;
+    const settlePerTickMs = 200;
+    const realSleep = (ms) => new Promise((r) => setTimeout(r, ms));
     let lastCtrl = pumps.map(() => 0);
     let largeJumpTicks = 0;
     for (let i = 0; i < ticks; i++) {
@@ -48,7 +58,7 @@ test('inflow ≫ capacity: pumps reach steady high-ctrl, no parking, no thrashin
       ps.setManualInflow(Q_IN, Date.now(), 'm3/s');
       advance(TICK_MS);
       ps.tick();
-      await new Promise((r) => setImmediate(r));
+      await realSleep(settlePerTickMs);
 
       const states = pumps.map((p) => p.state.getCurrentState());
       const ctrls  = pumps.map((p) => Number(p.state.getCurrentPosition?.()) || 0);