feat: 2048-pt FFT upgrade with decimation=4, 512 output bins, 6m spacing

Complete cross-layer upgrade from 1024-pt/64-bin to 2048-pt/512-bin FFT:

FPGA RTL (14+ modules):
- radar_params.vh: FFT_SIZE=2048, RANGE_BINS=512, 9-bit range, 6-bit stream
- fft_engine.v: 2048-pt FFT with XPM BRAM
- chirp_memory_loader_param.v: 2 segments x 2048 (was 4 x 1024)
- matched_filter_multi_segment.v: BRAM inference for overlap_cache, explicit ov_waddr
- mti_canceller.v: BRAM inference for prev_i/q arrays (was fabric FFs)
- doppler_processor.v: 16384-deep memory, 14-bit addressing
- cfar_ca.v: 512 rows, indentation fix
- radar_receiver_final.v: rising-edge detector for frame_complete, 11-bit sample_addr
- range_bin_decimator.v: 512 output bins
- usb_data_interface_ft2232h.v: bulk per-frame with Manhattan magnitude
- radar_mode_controller.v: XOR edge detector for toggle signals
- rx_gain_control.v: updated for new bin count

Python GUI + Protocol (8 files):
- radar_protocol.py: 512-bin bulk frame parser, LSB-first bitmap
- GUI_V65_Tk.py, v7/*.py: updated for 512 bins, 6m range resolution

Golden data + tests:
- All .hex/.csv/.npy golden references regenerated for 2048/512
- fft_twiddle_2048.mem added
- Deleted stale seg2/seg3 chirp mem files
- 9 new bulk frame cross-layer tests, deleted 6 stale per-sample tests
- Deleted stale tb_cross_layer_ft2232h.v and dead contract_parser functions
- Updated validate_mem_files.py for 2048/2-segment config

MCU: RadarSettings.cpp max_distance/map_size 1536->3072

All 4 CI jobs pass: 285 tests, 0 failures, 0 skips

9_Firmware/9_3_GUI/v7/workers.py

@@ -3,7 +3,7 @@ v7.workers — QThread-based workers and demo target simulator.
 
 Classes:
   - RadarDataWorker  — reads from FT2232H via production RadarAcquisition,
-                       parses 0xAA/0xBB packets, assembles 64x32 frames,
+                       parses 0xAA/0xBB packets, assembles 512x32 frames,
                        runs host-side DSP, emits PyQt signals.
   - GPSDataWorker    — reads GPS frames from STM32 CDC, emits GPSData signals.
   - TargetSimulator  — QTimer-based demo target generator.
@@ -52,11 +52,11 @@ class RadarDataWorker(QThread):
     and emits PyQt signals with results.
 
     Uses production radar_protocol.py for all packet parsing and frame
-    assembly (11-byte 0xAA data packets → 64x32 RadarFrame).
+    assembly (bulk frames or legacy 11-byte 0xAA data packets → 512x32 RadarFrame).
     For replay, use ReplayWorker instead.
 
     Signals:
-        frameReady(RadarFrame)    — a complete 64x32 radar frame
+        frameReady(RadarFrame)    — a complete 512x32 radar frame
         statusReceived(object)    — StatusResponse from FPGA
         targetsUpdated(list)      — list of RadarTarget after host-side DSP
         errorOccurred(str)        — error message
@@ -368,7 +368,7 @@ class TargetSimulator(QObject):
 
         for t in self._targets:
             new_range = t.range - t.velocity * 0.5
-            if new_range < 50 or new_range > 1536:
+            if new_range < 50 or new_range > 3072:
                 continue  # target exits coverage — drop it
 
             new_vel = max(-150, min(150, t.velocity + random.uniform(-2, 2)))