feat: add execution overlay types and extend ProcessDiagram with diagramLayout prop

Define the execution overlay type system (NodeExecutionState, IterationInfo,
DetailTab) and extend ProcessDiagramProps with optional overlay props. Add
diagramLayout prop so ExecutionDiagram can pass a pre-fetched layout by content
hash, bypassing the internal route-based fetch in useDiagramData.

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

ui/src/components/ExecutionDiagram/types.ts

@@ -0,0 +1,24 @@
+import type { components } from '../../api/schema';
+
+export type ExecutionDetail = components['schemas']['ExecutionDetail'];
+export type ProcessorNode = components['schemas']['ProcessorNode'];
+
+export interface NodeExecutionState {
+  status: 'COMPLETED' | 'FAILED';
+  durationMs: number;
+  /** True if this node's target sub-route failed (DIRECT/SEDA) */
+  subRouteFailed?: boolean;
+  /** True if trace data is available for this processor */
+  hasTraceData?: boolean;
+}
+
+export interface IterationInfo {
+  /** Current iteration index (0-based) */
+  current: number;
+  /** Total number of iterations */
+  total: number;
+  /** Type of iteration (determines label) */
+  type: 'loop' | 'split' | 'multicast';
+}
+
+export type DetailTab = 'info' | 'headers' | 'input' | 'output' | 'error' | 'config' | 'timeline';