feat: add waveform viewer endpoint and enhance UI with new tabs for history, units, monitor log, and sessions

sfm/server.py

@@ -402,6 +402,12 @@ def webapp():
     return str(Path(__file__).parent / "sfm_webapp.html")
 
 
+@app.get("/waveform", response_class=FileResponse)
+def waveform_viewer():
+    """Serve the standalone waveform viewer."""
+    return str(Path(__file__).parent / "waveform_viewer.html")
+
+
 @app.get("/device/info")
 def device_info(
     port:     Optional[str] = Query(None,             description="Serial port (e.g. COM5, /dev/ttyUSB0)"),