refactor: remove all ClickHouse code, old interfaces, and SQL migrations

- Delete all ClickHouse storage implementations and config
- Delete old core interfaces (ExecutionRepository, DiagramRepository, MetricsRepository, SearchEngine, RawExecutionRow)
- Delete ClickHouse SQL migration files
- Delete AbstractClickHouseIT
- Update controllers to use new store interfaces (DiagramStore, ExecutionStore)
- Fix IngestionService calls in controllers for new synchronous API
- Migrate all ITs from AbstractClickHouseIT to AbstractPostgresIT
- Fix count() syntax and remove ClickHouse-specific test assertions
- Update TreeReconstructionTest for new buildTree() method

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

cameleer3-server-app/src/test/java/com/cameleer3/server/app/search/OpenSearchIndexIT.java

@@ -24,8 +24,7 @@ class OpenSearchIndexIT extends AbstractPostgresIT {
 
     @Container
     static final OpensearchContainer<?> opensearch =
-            new OpensearchContainer<>("opensearchproject/opensearch:2.19.0")
-                    .withSecurityEnabled(false);
+            new OpensearchContainer<>("opensearchproject/opensearch:2.19.0");
 
     @DynamicPropertySource
     static void configureOpenSearch(DynamicPropertyRegistry registry) {
@@ -58,7 +57,7 @@ class OpenSearchIndexIT extends AbstractPostgresIT {
 
         SearchResult<ExecutionSummary> result = searchIndex.search(request);
         assertTrue(result.total() > 0);
-        assertEquals("search-1", result.items().get(0).executionId());
+        assertEquals("search-1", result.data().get(0).executionId());
     }
 
     @Test