G1: JUCE engine SHM chain rong POC - probe pass, khong lag them

app/core/fx_realtime.py

@@ -162,7 +162,8 @@ class FxRealtimeSession:
         return out
 
     def _spawn(self):
-        exe = find_fx_bridge_exe()
+        juce_exe = os.getenv("SF_JUCE_FX_BRIDGE_PATH", "").strip()
+        exe = juce_exe or find_fx_bridge_exe()
         if not exe:
             raise RuntimeError("Không tìm thấy fx_vst_bridge.exe")
         job = {
@@ -174,8 +175,12 @@ class FxRealtimeSession:
         fd, self._job_path = tempfile.mkstemp(suffix=".json", prefix="fxrt_")
         with os.fdopen(fd, "w", encoding="utf-8") as f:
             json.dump(job, f)
-        cmd = [exe, "--realtime-fx", self._job_path, "--shm", self.name,
-               "--parent", str(os.getpid())]
+        if juce_exe:
+            cmd = [exe, "--juce-fx", self._job_path, "--shm", self.name,
+                   "--parent", str(os.getpid())]
+        else:
+            cmd = [exe, "--realtime-fx", self._job_path, "--shm", self.name,
+                   "--parent", str(os.getpid())]
         # FXRT_BRIDGE_LOG=<path>: bat stderr bridge (FxRTPerf) vao file — chan
         # doan outFull/drop; mac dinh DEVNULL nhu cu.
         # V34 diag: mac dinh ghi FxRTPerf vao fxrt_bridge.log de phan tich