fix(gui): P-1 — RadarDataWorker __init__ initialises runtime attrs

Audit P-1 (2026-05-02): _frame_queue, _acquisition, and frame counters
were stranded inside set_waveform() due to indentation drift.  The
dashboard constructs RadarDataWorker and calls .start() directly
without ever calling set_waveform, so live FT2232H acquisition crashes
with AttributeError on first frame access in run().

Move the init block back into __init__; set_waveform now only sets
self._waveform.  Add TestRadarDataWorkerInit covering both:
- attrs present after bare __init__ (no set_waveform required)
- set_waveform does not reset runtime counters

Test result: test_v7 102/102 PASS in radar_venv (was 100/100 + 2 new).

9_Firmware/9_3_GUI/v7/workers.py

@@ -91,9 +91,6 @@ class RadarDataWorker(QThread):
         self._waveform = WaveformConfig()
         self._running = False
 
-    def set_waveform(self, wf) -> None:
-        self._waveform = wf
-
         # Frame queue for production RadarAcquisition → this thread
         self._frame_queue: queue.Queue = queue.Queue(maxsize=4)
 
@@ -105,6 +102,9 @@ class RadarDataWorker(QThread):
         self._byte_count = 0
         self._error_count = 0
 
+    def set_waveform(self, wf) -> None:
+        self._waveform = wf
+
     def stop(self):
         self._running = False
         if self._acquisition: