feat: update OpenAPI spec and TypeScript types for execution overlay

Add iteration fields (loopIndex, loopSize, splitIndex, splitSize,
multicastIndex) to ProcessorNode schema. Add new endpoint path
/executions/{executionId}/processors/by-id/{processorId}/snapshot.
Remove stale diagramNodeId field that was dropped in V6 migration.

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

ui/src/api/schema.d.ts

@@ -735,6 +735,23 @@ export interface paths {
         patch?: never;
         trace?: never;
     };
+    "/executions/{executionId}/processors/by-id/{processorId}/snapshot": {
+        parameters: {
+            query?: never;
+            header?: never;
+            path?: never;
+            cookie?: never;
+        };
+        /** Get exchange snapshot for a processor by processorId */
+        get: operations["getProcessorSnapshotById"];
+        put?: never;
+        post?: never;
+        delete?: never;
+        options?: never;
+        head?: never;
+        patch?: never;
+        trace?: never;
+    };
     "/diagrams": {
         parameters: {
             query?: never;
@@ -1620,7 +1637,16 @@ export interface components {
             endTime: string;
             /** Format: int64 */
             durationMs: number;
-            diagramNodeId: string;
+            /** Format: int32 */
+            loopIndex?: number;
+            /** Format: int32 */
+            loopSize?: number;
+            /** Format: int32 */
+            splitIndex?: number;
+            /** Format: int32 */
+            splitSize?: number;
+            /** Format: int32 */
+            multicastIndex?: number;
             errorMessage: string;
             errorStackTrace: string;
             attributes: {
@@ -3637,6 +3663,42 @@ export interface operations {
             };
         };
     };
+    getProcessorSnapshotById: {
+        parameters: {
+            query?: never;
+            header?: never;
+            path: {
+                executionId: string;
+                processorId: string;
+            };
+            cookie?: never;
+        };
+        requestBody?: never;
+        responses: {
+            /** @description Snapshot data */
+            200: {
+                headers: {
+                    [name: string]: unknown;
+                };
+                content: {
+                    "*/*": {
+                        [key: string]: string;
+                    };
+                };
+            };
+            /** @description Snapshot not found */
+            404: {
+                headers: {
+                    [name: string]: unknown;
+                };
+                content: {
+                    "*/*": {
+                        [key: string]: string;
+                    };
+                };
+            };
+        };
+    };
     findByApplicationAndRoute: {
         parameters: {
             query: {