CLAUDE: Save mixed DNN input (-SYNTHMIX) after synth injection

The CONV2D images are saved BEFORE synth injection (real-only), so the actual
DNN input (LoG-conditioned real bg + injected synth) was no longer visible once
the mixing order moved to post-conditioning. Add a per-selected-level save of
dpixels_pyramid right after injection: getBaseName()+"-SYNTHMIX"+("B" if over
real bg)+("-SUBAVG" if avg-subtracted)+"-LEVn", full-frame (640x512), same
timestamps - what the network actually sees. Gated by save_LoG_pixels.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

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

@@ -1051,6 +1051,18 @@ public class CuasDetectRT {
    			}
    			System.out.println(now()+" detectTargets(): injected synthetic grid (tiled "+n_synth+" frames) into selected pyramid levels"
    					+ (synth_bg ? " (over real background)" : " (CLEAN - background zeroed, curt_synth_bg=false)")); // By Claude on 06/15/2026
+   			// Save the ACTUAL DNN input after mixing: LoG-conditioned real bg (avg-subtracted if curt_subtract_avg)
+   			// + injected synth, full-frame per selected level, same timestamps - what the network really sees. By Claude on 06/16/2026
+   			if (save_LoG_pixels) {
+   				for (int nlev = 0; nlev < pyramid_levels; nlev++) {
+   					if (!c5LevelSelected(c5_levels, nlev) || (dpixels_pyramid[nlev] == null)) continue;
+   					String title_mix = getBaseName()+"-SYNTHMIX"+(synth_bg?"B":"")+(clt_parameters.imp.curt_subtract_avg?"-SUBAVG":"")+"-LEV"+nlev;
+   					ImagePlus imp_mix = ShowDoubleFloatArrays.makeArrays(
+   							dpixels_pyramid[nlev], getWidth(), getHeight(), title_mix, ts_pyramid[nlev]);
+   					imp_mix.setDisplayRange(CuasRTUtils.IMP_MINMAX[0], CuasRTUtils.IMP_MINMAX[1]);
+   					QuadCLTCPU.saveImagePlusInDirectory(imp_mix, getModelDirectory());
+   				}
+   			}
    		}
    		// Direct pixel-domain fine-velocity path (-C5P): bypass the 3x3 coarse stage -    // By Claude on 06/11/2026
    		// a single-stage velocity-matched filter straight on the LoG+LReLU frames of     // By Claude on 06/11/2026