chore(tests): silence three noisy warnings in deploy-gate output

deploy.sh's vitest + pytest output was polluted with three benign
but loud warnings that buried real signal:

1. AVRSimulator.start() unconditionally read `window.__spiceDebug`.
   In node-side vitest runs `window` is undefined → ReferenceError
   → console.warn('[spice] debug dump failed', e). Logged once per
   AVR test. Guarded with `typeof window !== 'undefined'`; in
   production the browser path is unchanged.

2. pinPositionCalculator.calculatePinPosition() warned every time
   document.getElementById returned null. In node-side tests there
   is no real DOM and every wire-related test triggers the warning
   for every component. Skip the console.warn when
   import.meta.env.MODE === 'test' (vitest sets MODE=test); the
   function still returns null and production retains the
   actionable warning for unmounted components.

3. test_esp32_wifi_args.py::test_start_instance_accepts_wifi_params
   mocked asyncio.create_task with no side_effect, so the coroutine
   from self._boot(...) leaked and triggered a "coroutine never
   awaited" RuntimeWarning. Mock now closes the coroutine.

After fixes:
  frontend tests:  0 spice/pinPositionCalculator stderr lines
  backend tests:   259 passed, 15 skipped, 1 warning (starlette
                   third-party python_multipart deprecation —
                   not ours, fixed when starlette updates).

frontend/src/simulation/AVRSimulator.ts

@@ -508,12 +508,12 @@ export class AVRSimulator {
 
     this.running = true;
     console.log('Starting AVR simulation...');
-    try {
+    // Browser-only debug hook. Guarded so node-side vitest runs don't
+    // ReferenceError on `window` and spam stderr.
+    if (typeof window !== 'undefined') {
       const dbg = (window as unknown as { __spiceDebug?: () => void }).__spiceDebug;
       if (typeof dbg === 'function') dbg();
       else console.warn('[spice] __spiceDebug not attached — startSimulation never called');
-    } catch (e) {
-      console.warn('[spice] debug dump failed', e);
     }
 
     // ATmega328p @ 16MHz

frontend/src/utils/pinPositionCalculator.ts

@@ -37,14 +37,23 @@ export function calculatePinPosition(
   // Get the DOM element
   const element = document.getElementById(componentId);
   if (!element) {
+    // Don't spam the vitest log: in node-side tests there's no real
+    // DOM and this function gets called per-wire on every render
+    // (each one logs "Component foo not found in DOM"). In a browser
+    // the warning is actionable — a wire references a component that
+    // failed to mount.
+    if (import.meta.env.MODE !== 'test') {
       console.warn(`[pinPositionCalculator] Component ${componentId} not found in DOM`);
+    }
     return null;
   }
 
   // Access the pinInfo property (all wokwi-elements expose this)
   const pinInfo = (element as any).pinInfo;
   if (!pinInfo || !Array.isArray(pinInfo)) {
+    if (import.meta.env.MODE !== 'test') {
       console.warn(`[pinPositionCalculator] Component ${componentId} does not have pinInfo`);
+    }
     return null;
   }
 

test/backend/unit/test_esp32_wifi_args.py

@@ -101,8 +101,18 @@ class TestEspQemuManagerWifiArgs(unittest.TestCase):
         """start_instance should accept wifi_enabled and wifi_hostfwd_port."""
         from app.services.esp_qemu_manager import EspQemuManager
         mgr = EspQemuManager()
-        # Should not raise
-        with patch('asyncio.create_task'):
+
+        # start_instance calls `asyncio.create_task(self._boot(...))`. The
+        # `_boot(...)` call creates a coroutine BEFORE create_task sees it,
+        # so simply mocking create_task with no side-effect lets the
+        # coroutine leak and trigger a "coroutine never awaited"
+        # RuntimeWarning in the test log.  Close the coroutine inside the
+        # mock to consume it cleanly.
+        def consume_coroutine(coro):
+            coro.close()
+            return MagicMock()
+
+        with patch('asyncio.create_task', side_effect=consume_coroutine):
             mgr.start_instance(
                 'test-client', 'esp32', MagicMock(),
                 firmware_b64=None,