feat: expose iteration/iterationSize fields for diagram overlay

Replace synthetic wrapper node approach with direct iteration fields:
- ProcessorNode gains iteration (child's index) and iterationSize
  (container's total) fields, populated from ClickHouse flat records
- Frontend hooks detect iteration containers from iterationSize != null
  instead of scanning for wrapper processorTypes
- useExecutionOverlay filters children by iteration field instead of
  wrapper nodes, eliminating ITERATION_WRAPPER_TYPES entirely
- Cleaner data contract: API returns exactly what the DB stores

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/DetailService.java

@@ -101,7 +101,7 @@ public class DetailService {
                     p.getDurationMs(),
                     p.getErrorMessage(), p.getErrorStackTrace(),
                     p.getAttributes() != null ? new LinkedHashMap<>(p.getAttributes()) : null,
-                    null, null, null, null, null,
+                    null, null, null, null, null, null, null,
                     p.getResolvedEndpointUri(),
                     p.getErrorType(), p.getErrorCategory(),
                     p.getRootCauseType(), p.getRootCauseMessage(),
@@ -144,7 +144,7 @@ public class DetailService {
                     p.errorMessage(), p.errorStacktrace(),
                     parseAttributes(p.attributes()),
                     p.iteration(), p.iterationSize(),
-                    null, null, null,
+                    null, null, null, null, null,
                     p.resolvedEndpointUri(),
                     p.errorType(), p.errorCategory(),
                     p.rootCauseType(), p.rootCauseMessage(),
@@ -188,6 +188,7 @@ public class DetailService {
                     p.durationMs() != null ? p.durationMs() : 0L,
                     p.errorMessage(), p.errorStacktrace(),
                     parseAttributes(p.attributes()),
+                    null, null,
                     p.loopIndex(), p.loopSize(),
                     p.splitIndex(), p.splitSize(),
                     p.multicastIndex(),

cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/ProcessorNode.java

@@ -22,6 +22,8 @@ public final class ProcessorNode {
     private final String errorMessage;
     private final String errorStackTrace;
     private final Map<String, String> attributes;
+    private final Integer iteration;
+    private final Integer iterationSize;
     private final Integer loopIndex;
     private final Integer loopSize;
     private final Integer splitIndex;
@@ -44,6 +46,7 @@ public final class ProcessorNode {
                          Instant startTime, Instant endTime, long durationMs,
                          String errorMessage, String errorStackTrace,
                          Map<String, String> attributes,
+                         Integer iteration, Integer iterationSize,
                          Integer loopIndex, Integer loopSize,
                          Integer splitIndex, Integer splitSize,
                          Integer multicastIndex,
@@ -63,6 +66,8 @@ public final class ProcessorNode {
         this.errorMessage = errorMessage;
         this.errorStackTrace = errorStackTrace;
         this.attributes = attributes;
+        this.iteration = iteration;
+        this.iterationSize = iterationSize;
         this.loopIndex = loopIndex;
         this.loopSize = loopSize;
         this.splitIndex = splitIndex;
@@ -95,6 +100,8 @@ public final class ProcessorNode {
     public String getErrorMessage() { return errorMessage; }
     public String getErrorStackTrace() { return errorStackTrace; }
     public Map<String, String> getAttributes() { return attributes; }
+    public Integer getIteration() { return iteration; }
+    public Integer getIterationSize() { return iterationSize; }
     public Integer getLoopIndex() { return loopIndex; }
     public Integer getLoopSize() { return loopSize; }
     public Integer getSplitIndex() { return splitIndex; }

cameleer3-server-core/src/test/java/com/cameleer3/server/core/detail/TreeReconstructionTest.java

@@ -192,17 +192,23 @@ class TreeReconstructionTest {
 
     @Test
     void buildTree_seqBasedModel_iterationFields() {
-        // Verify iteration/iterationSize are populated as loopIndex/loopSize
+        // Verify iteration/iterationSize are populated on the correct nodes
         List<ProcessorRecord> processors = List.of(
-                procWithSeq("loop1", "loop", "COMPLETED", 1, null, null, null),
-                procWithSeq("body", "log", "COMPLETED", 2, 1, 5, 10)
+                procWithSeq("split1", "split", "COMPLETED", 1, null, null, 3),
+                procWithSeq("body", "log", "COMPLETED", 2, 1, 0, null),
+                procWithSeq("body", "log", "COMPLETED", 3, 1, 1, null),
+                procWithSeq("body", "log", "COMPLETED", 4, 1, 2, null)
         );
 
         List<ProcessorNode> roots = detailService.buildTree(processors);
 
         assertThat(roots).hasSize(1);
-        ProcessorNode child = roots.get(0).getChildren().get(0);
-        assertThat(child.getLoopIndex()).isEqualTo(5);
-        assertThat(child.getLoopSize()).isEqualTo(10);
+        ProcessorNode container = roots.get(0);
+        assertThat(container.getIterationSize()).isEqualTo(3);
+        assertThat(container.getIteration()).isNull();
+        assertThat(container.getChildren()).hasSize(3);
+        assertThat(container.getChildren().get(0).getIteration()).isEqualTo(0);
+        assertThat(container.getChildren().get(1).getIteration()).isEqualTo(1);
+        assertThat(container.getChildren().get(2).getIteration()).isEqualTo(2);
     }
 }