fix: update remaining ITs for synchronous ingestion and PostgreSQL storage

- SearchControllerIT: remove @TestInstance(PER_CLASS), use @BeforeEach with
  static guard, fix table name (route_executions -> executions), remove
  Awaitility polling
- OpenSearchIndexIT: replace Thread.sleep with explicit index refresh via
  OpenSearchClient
- DiagramLinkingIT: fix table name, remove Awaitility awaits (writes are
  synchronous)
- IngestionSchemaIT: rewrite queries for PostgreSQL relational model
  (processor_executions table instead of ClickHouse array columns)
- PostgresStatsStoreIT: use explicit time bounds in
  refresh_continuous_aggregate calls
- IngestionService: populate diagramContentHash during execution ingestion
  by looking up the latest diagram for the route+agent

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

cameleer3-server-core/src/main/java/com/cameleer3/server/core/ingestion/IngestionService.java

@@ -69,6 +69,9 @@ public class IngestionService {
 
     private ExecutionRecord toExecutionRecord(String agentId, String groupName,
                                                RouteExecution exec) {
+        String diagramHash = diagramStore
+                .findContentHashForRoute(exec.getRouteId(), agentId)
+                .orElse("");
         return new ExecutionRecord(
                 exec.getExchangeId(), exec.getRouteId(), agentId, groupName,
                 exec.getStatus() != null ? exec.getStatus().name() : "RUNNING",
@@ -76,7 +79,7 @@ public class IngestionService {
                 exec.getStartTime(), exec.getEndTime(),
                 exec.getDurationMs(),
                 exec.getErrorMessage(), exec.getErrorStackTrace(),
-                null // diagramContentHash set separately
+                diagramHash
         );
     }