fix(pagination): add insert_id UUID tiebreak to cursor keyset

Same-millisecond rows were silently skipped between pages because the
log cursor had no tiebreak and the events cursor tied by instance_id
(which also collides when one instance emits multiple events within a
millisecond). Add an insert_id UUID (DEFAULT generateUUIDv4()) column
to both logs and agent_events, order by (timestamp, insert_id)
consistently, and encode the cursor as 'timestamp|insert_id'. Existing
data is materialized via ALTER TABLE MATERIALIZE COLUMN (one-time
background mutation).

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

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

@@ -371,4 +371,30 @@ class ClickHouseLogStoreIT {
         assertThat(result.data()).extracting(LogEntryResult::message)
                 .containsExactlyInAnyOrder("app msg", "container msg");
     }
+
+    @Test
+    void search_cursorPagination_sameMillisecond_doesNotSkip() {
+        Instant ts = Instant.parse("2026-04-17T10:00:00Z");
+        // Insert 5 rows at the exact same timestamp
+        java.util.List<LogEntry> batch = new java.util.ArrayList<>();
+        for (int i = 0; i < 5; i++) {
+            batch.add(entry(ts, "INFO", "logger", "msg-" + i, "t1", null, null));
+        }
+        store.indexBatch("agent-1", "my-app", batch);
+
+        // Page through with limit 2; across 3 pages we must see all 5 distinct messages, no duplicates
+        java.util.Set<String> seen = new java.util.HashSet<>();
+        String cursor = null;
+        for (int page = 0; page < 10; page++) {
+            LogSearchResponse resp = store.search(new LogSearchRequest(
+                    null, null, "my-app", null, null, null, null, null,
+                    null, null, cursor, 2, "desc"));
+            for (LogEntryResult r : resp.data()) {
+                assertThat(seen.add(r.message())).as("duplicate row returned: " + r.message()).isTrue();
+            }
+            cursor = resp.nextCursor();
+            if (!resp.hasMore()) break;
+        }
+        assertThat(seen).containsExactlyInAnyOrder("msg-0", "msg-1", "msg-2", "msg-3", "msg-4");
+    }
 }

cameleer-server-app/src/test/java/com/cameleer/server/app/storage/ClickHouseAgentEventRepositoryIT.java

@@ -115,25 +115,24 @@ class ClickHouseAgentEventRepositoryIT {
     }
 
     @Test
-    void queryPage_tiebreakByInstanceIdAsc_whenTimestampsEqual() {
+    void queryPage_tiebreak_sameMillisecond_returnsAllRowsNoDuplicates() {
         Instant ts = Instant.parse("2026-04-01T10:00:00Z");
-        insertAt("agent-z", "app-a", "TICK", "z", ts);
         insertAt("agent-a", "app-a", "TICK", "a", ts);
-        insertAt("agent-m", "app-a", "TICK", "m", ts);
+        insertAt("agent-b", "app-a", "TICK", "b", ts);
+        insertAt("agent-c", "app-a", "TICK", "c", ts);
 
-        com.cameleer.server.core.agent.AgentEventPage p1 =
-                repo.queryPage(null, null, null, null, null, null, 2);
-        assertThat(p1.data()).hasSize(2);
-        // (timestamp DESC, instance_id ASC): ties resolve to a, m, z
-        assertThat(p1.data().get(0).instanceId()).isEqualTo("agent-a");
-        assertThat(p1.data().get(1).instanceId()).isEqualTo("agent-m");
-        assertThat(p1.hasMore()).isTrue();
-
-        com.cameleer.server.core.agent.AgentEventPage p2 =
-                repo.queryPage(null, null, null, null, null, p1.nextCursor(), 2);
-        assertThat(p2.data()).hasSize(1);
-        assertThat(p2.data().get(0).instanceId()).isEqualTo("agent-z");
-        assertThat(p2.hasMore()).isFalse();
+        java.util.Set<String> seen = new java.util.HashSet<>();
+        String cursor = null;
+        for (int page = 0; page < 10; page++) {
+            com.cameleer.server.core.agent.AgentEventPage p =
+                    repo.queryPage(null, null, null, null, null, cursor, 1);
+            for (com.cameleer.server.core.agent.AgentEventRecord r : p.data()) {
+                assertThat(seen.add(r.instanceId())).as("duplicate row returned: " + r.instanceId()).isTrue();
+            }
+            cursor = p.nextCursor();
+            if (!p.hasMore()) break;
+        }
+        assertThat(seen).containsExactlyInAnyOrder("agent-a", "agent-b", "agent-c");
     }
 
     @Test
@@ -148,7 +147,7 @@ class ClickHouseAgentEventRepositoryIT {
     }
 
     @Test
-    void queryPage_malformedCursor_emptyInstanceId_throws() {
+    void queryPage_malformedCursor_emptyInsertId_throws() {
         String raw = "2026-04-01T10:00:00Z|";
         String cursor = java.util.Base64.getUrlEncoder().withoutPadding()
                 .encodeToString(raw.getBytes(java.nio.charset.StandardCharsets.UTF_8));