CLAUDE: Add showConvKernel5d(ROI) visualization and wire curt_save_c5rect

New CuasRTUtils.showConvKernel5d(data, roi, titles, title): renders the
vout_dim×vout_dim velocity map for each ROI pixel as a tiled flat image,
with a 1-px NaN separator grid between pixel blocks (visible in ImageJ).
Sub-pixels (pixel_decimate>1) tile within each block.

CuasDetectRT: add curt_save_c5rect save calls at level-0 and each pyramid
level (title suffix "-RECT", "-LEVn-RECT"). curt_save_c5full path unchanged.
Co-authored-by: Claude <claude@elphel.com>

src/main/java/com/elphel/imagej/cuas/rt/CuasDetectRT.java

@@ -306,6 +306,14 @@ public class CuasDetectRT {
    					title_conv5d);
    			QuadCLTCPU.saveImagePlusInDirectory(imp_5d, getModelDirectory());
    		}
+   		if (curt_save_c5rect && num_5d_lev0 > 0) {
+   			ImagePlus imp_5d_rect = cuasRTUtils.showConvKernel5d(
+   					dpixels_5d_pyramid[0],
+   					curt_save_select,
+   					ts_5d_lev0,
+   					title_conv5d+"-RECT");
+   			QuadCLTCPU.saveImagePlusInDirectory(imp_5d_rect, getModelDirectory());
+   		}
    		for (int nlev = 0; nlev < pyramid_levels; nlev++) {
    	       	if (save_LoG_pixels) {
    	       		String title_conv2d_lev = getBaseName()+SUFFIX_CONV2D+"-PSF"+d2s(cuasRTUtils.getPsfRadius())+
@@ -374,6 +382,14 @@ public class CuasDetectRT {
    		   					title_conv5d+"-LEV"+(nlev+1));
    		   			QuadCLTCPU.saveImagePlusInDirectory(imp_5d, getModelDirectory());
    		   		}
+   		   		if (curt_save_c5rect && num_5d_lev > 0) {
+   		   			ImagePlus imp_5d_rect = cuasRTUtils.showConvKernel5d(
+   		   					dpixels_5d_pyramid[nlev+1],
+   		   					curt_save_select,
+   		   					ts_5d_lev,
+   		   					title_conv5d+"-LEV"+(nlev+1)+"-RECT");
+   		   			QuadCLTCPU.saveImagePlusInDirectory(imp_5d_rect, getModelDirectory());
+   		   		}
    			}
    		}
    		return null;

src/main/java/com/elphel/imagej/cuas/rt/CuasRTUtils.java

 package com.elphel.imagej.cuas.rt;
 
+import java.awt.Rectangle;
 import java.util.Arrays;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -1071,4 +1072,86 @@ public class CuasRTUtils {
     	return imp;
     }
 
+    /**
+     * Render fine-velocity output for a pixel ROI as a flat image stack (one slice per scene).
+     * For each pixel in the ROI a (vout_dim × vout_dim) velocity-map square is drawn.
+     * Squares are tiled in the output image with a 1-pixel NaN separator column/row
+     * (renders as visible grid in ImageJ). Sub-pixels (pixel_decimate > 1) tile inside each square.
+     *
+     * Output dimensions:
+     *   width  = roi.width  * (vout_dim + 1) * sub_dim
+     *   height = roi.height * (vout_dim + 1) * sub_dim
+     *
+     * @param data         [nscene][width*height][nsub][nvel] — output of convolve3d
+     * @param roi          pixel rectangle to render (full-image coordinates)
+     * @param scene_titles per-slice labels, or null
+     * @param title        image title, or null
+     */
+    public ImagePlus showConvKernel5d(
+    		double [][][][] data,
+    		Rectangle       roi,
+    		String []       scene_titles,
+    		String          title) {
+    	int num_scenes = data.length;
+    	int num_vout   = kernel5d[0].length;
+    	int vout_dim   = (int) Math.sqrt(num_vout);
+    	int num_sub    = kernel5d[0][0].length;
+    	int sub_dim    = (int) Math.sqrt(num_sub);
+
+    	int roi_width  = roi.width  * (vout_dim + 1) * sub_dim;
+    	int roi_height = roi.height * (vout_dim + 1) * sub_dim;
+    	int block_w    = (vout_dim + 1) * sub_dim;
+    	int block_h    = (vout_dim + 1) * sub_dim;
+
+    	if (title == null) title = "CONV5D-ROI";
+    	if (scene_titles == null) {
+    		scene_titles = new String[num_scenes];
+    		for (int i = 0; i < scene_titles.length; i++) {
+    			scene_titles[i] = String.format("scene-%03d", i);
+    		}
+    	}
+
+    	double [][] rendered = new double[num_scenes][roi_width * roi_height];
+    	for (double [] slice : rendered) Arrays.fill(slice, Double.NaN);
+
+    	for (int nscene = 0; nscene < num_scenes; nscene++) {
+    		for (int py_roi = 0; py_roi < roi.height; py_roi++) {
+    			int py_img = roi.y + py_roi;
+    			if (py_img < 0 || py_img >= height) continue;
+    			for (int px_roi = 0; px_roi < roi.width; px_roi++) {
+    				int px_img = roi.x + px_roi;
+    				if (px_img < 0 || px_img >= width) continue;
+    				int pixel_idx = py_img * width + px_img;
+    				int block_x   = px_roi * block_w;
+    				int block_y   = py_roi * block_h;
+    				double [][]   pix_data = data[nscene][pixel_idx]; // [nsub][nvel]
+    				for (int sy = 0; sy < sub_dim; sy++) {
+    					for (int sx = 0; sx < sub_dim; sx++) {
+    						int sub_idx = sy * sub_dim + sx;
+    						int slot_x  = block_x + sx * (vout_dim + 1);
+    						int slot_y  = block_y + sy * (vout_dim + 1);
+    						for (int vy = 0; vy < vout_dim; vy++) {
+    							for (int vx = 0; vx < vout_dim; vx++) {
+    								int v_out_idx = vy * vout_dim + vx;
+    								int rx = slot_x + vx;
+    								int ry = slot_y + vy;
+    								rendered[nscene][ry * roi_width + rx] = pix_data[sub_idx][v_out_idx];
+    							}
+    						}
+    					}
+    				}
+    			}
+    		}
+    	}
+
+    	ImagePlus imp = ShowDoubleFloatArrays.makeArrays(
+    			rendered,
+    			roi_width,
+    			roi_height,
+    			title,
+    			scene_titles);
+    	imp.setDisplayRange(IMP_MINMAX[0], IMP_MINMAX[1]);
+    	return imp;
+    }
+
 }