Claude: FAIL_PENDING refactoring — migrate first loop from motion_sequence to target_sequence_multi

- Add FAIL_PENDING=-1 sentinel constant to CuasMotionLMA
- Add initFromMotionSequence(): clones motion entries into target_sequence_multi as sentinels
  (RSLT_FAIL=FAIL_PENDING, RSLT_CENTERED=CENTERED_NO, RSLT_QSCORE=initial RSLT_MSCORE)
- Add syncMotionScoreToSentinels(): keeps sentinel QSCORE current after each getEffectiveStrengthMV
- Decouple use_motion/select_new flags in filter5Targets from motion_sequence==null
- Add motion==null paths in filter5Targets: prohibit setup and is-max ranking for FAIL_PENDING sentinels
- Extend filter5Targets marking step to cover FAIL_PENDING sentinels (use_motion=true, motion==null)
- Update extendMotionScan center-detection to accept FAIL_PENDING as valid center state
- First loop in locateAndFreezeTargetsMulti: call initFromMotionSequence, syncMotionScoreToSentinels;
  pass null to filter5Targets; use applyFilter(target_sequence_multi); use getRemain(target_sequence_multi)
- getRemain(target_sequence_multi): count FAIL_PENDING+CENTERED_NO in num_noncentered
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main/java/com/elphel/imagej/cuas/CuasMotionLMA.java

@@ -124,6 +124,7 @@ public class CuasMotionLMA {
 				"FLOG-px","FLOG-pY","FLOG-DISP","FLOG-range","infinity",
 				"GTarget-ID","Vel-away", "Vel-right", "Vel-up","Range-linear"};
 	public static final String EXTRA_SLICE_DISCARD_ON_LOAD = "Targets"; 
+	public static final int FAIL_PENDING =  -1; // By Claude on 05/07/2026: motion sentinel — tile tracked but not yet processed by LMA
 	public static final int FAIL_NONE =      0;
 	public static final int FAIL_MOTION =    1;  // motion strength/fraction too low
 	public static final int FAIL_NO_MAX =    2;  // no suitable local maximum