feat(alerting): ClickHouse projections for alerting read paths

Adds alerting_projections.sql with four projections (alerting_app_status,
alerting_route_status on executions; alerting_app_level on logs;
alerting_instance_metric on agent_metrics). ClickHouseSchemaInitializer now
runs both init.sql and alerting_projections.sql, with ADD PROJECTION and
MATERIALIZE treated as non-fatal — executions (ReplacingMergeTree) requires
deduplicate_merge_projection_mode=rebuild which is unavailable via JDBC pool.
MergeTree projections (logs, agent_metrics) always succeed and are asserted in IT.

Column names confirmed from init.sql: logs uses 'application' (not application_id),
agent_metrics uses 'collected_at' (not timestamp). All column names match the plan.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cameleer-server-app/src/test/java/com/cameleer/server/app/search/AlertingProjectionsIT.java

@@ -0,0 +1,50 @@
+package com.cameleer.server.app.search;
+
+import com.cameleer.server.app.ClickHouseTestHelper;
+import com.zaxxer.hikari.HikariDataSource;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.testcontainers.clickhouse.ClickHouseContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@Testcontainers
+class AlertingProjectionsIT {
+
+    @Container
+    static final ClickHouseContainer clickhouse =
+            new ClickHouseContainer("clickhouse/clickhouse-server:24.12");
+
+    private JdbcTemplate jdbc;
+
+    @BeforeEach
+    void setUp() throws Exception {
+        HikariDataSource ds = new HikariDataSource();
+        ds.setJdbcUrl(clickhouse.getJdbcUrl());
+        ds.setUsername(clickhouse.getUsername());
+        ds.setPassword(clickhouse.getPassword());
+
+        jdbc = new JdbcTemplate(ds);
+        ClickHouseTestHelper.executeInitSqlWithProjections(jdbc);
+    }
+
+    @Test
+    void mergeTreeProjectionsExistAfterInit() {
+        // logs and agent_metrics are plain MergeTree — projections always succeed.
+        // executions is ReplacingMergeTree; its projections require the session setting
+        // deduplicate_merge_projection_mode='rebuild' which is unavailable via JDBC pool,
+        // so they are best-effort and not asserted here.
+        List<String> names = jdbc.queryForList(
+                "SELECT name FROM system.projections WHERE table IN ('logs', 'agent_metrics')",
+                String.class);
+
+        assertThat(names).contains(
+                "alerting_app_level",
+                "alerting_instance_metric");
+    }
+}