Fix bucket alignment: compute 5-min floor in Java, not ClickHouse SQL

JDBC sends Timestamp params as strings, causing toStartOfFiveMinutes()
to fail with 'Illegal type String'. Floor to 5-minute boundaries in
Java instead and pass plain bucket >= ? comparisons.

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

cameleer3-server-app/src/main/java/com/cameleer3/server/app/search/ClickHouseSearchEngine.java

@@ -99,8 +99,8 @@ public class ClickHouseSearchEngine implements SearchEngine {
         // Current period — read from rollup
         var conditions = new ArrayList<String>();
         var params = new ArrayList<Object>();
-        conditions.add("bucket >= toStartOfFiveMinutes(?)");
-        params.add(Timestamp.from(from));
+        conditions.add("bucket >= ?");
+        params.add(Timestamp.from(floorToFiveMinutes(from)));
         conditions.add("bucket <= ?");
         params.add(Timestamp.from(to));
         addScopeFilters(routeId, agentIds, conditions, params);
@@ -139,8 +139,8 @@ public class ClickHouseSearchEngine implements SearchEngine {
         Instant prevTo = prevFrom.plus(window);
         var prevConditions = new ArrayList<String>();
         var prevParams = new ArrayList<Object>();
-        prevConditions.add("bucket >= toStartOfFiveMinutes(?)");
-        prevParams.add(Timestamp.from(prevFrom));
+        prevConditions.add("bucket >= ?");
+        prevParams.add(Timestamp.from(floorToFiveMinutes(prevFrom)));
         prevConditions.add("bucket <= ?");
         prevParams.add(Timestamp.from(prevTo));
         addScopeFilters(routeId, agentIds, prevConditions, prevParams);
@@ -165,8 +165,8 @@ public class ClickHouseSearchEngine implements SearchEngine {
         Instant todayStart = Instant.now().truncatedTo(java.time.temporal.ChronoUnit.DAYS);
         var todayConditions = new ArrayList<String>();
         var todayParams = new ArrayList<Object>();
-        todayConditions.add("bucket >= toStartOfFiveMinutes(?)");
-        todayParams.add(Timestamp.from(todayStart));
+        todayConditions.add("bucket >= ?");
+        todayParams.add(Timestamp.from(floorToFiveMinutes(todayStart)));
         addScopeFilters(routeId, agentIds, todayConditions, todayParams);
         String todayWhere = " WHERE " + String.join(" AND ", todayConditions);
 
@@ -194,8 +194,8 @@ public class ClickHouseSearchEngine implements SearchEngine {
 
         var conditions = new ArrayList<String>();
         var params = new ArrayList<Object>();
-        conditions.add("bucket >= toStartOfFiveMinutes(?)");
-        params.add(Timestamp.from(from));
+        conditions.add("bucket >= ?");
+        params.add(Timestamp.from(floorToFiveMinutes(from)));
         conditions.add("bucket <= ?");
         params.add(Timestamp.from(to));
         addScopeFilters(routeId, agentIds, conditions, params);
@@ -326,6 +326,14 @@ public class ClickHouseSearchEngine implements SearchEngine {
         }
     }
 
+    /**
+     * Floor an Instant to the start of its 5-minute bucket.
+     */
+    private static Instant floorToFiveMinutes(Instant instant) {
+        long epochSecond = instant.getEpochSecond();
+        return Instant.ofEpochSecond(epochSecond - (epochSecond % 300));
+    }
+
     /**
      * Escape special LIKE characters to prevent LIKE injection.
      */