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/main/resources/clickhouse/init.sql

@@ -327,7 +327,8 @@ CREATE TABLE IF NOT EXISTS agent_events (
     instance_id    LowCardinality(String),
     application_id LowCardinality(String),
     event_type     LowCardinality(String),
-    detail         String DEFAULT ''
+    detail         String DEFAULT '',
+    insert_id      UUID DEFAULT generateUUIDv4()
 )
 ENGINE = MergeTree()
 PARTITION BY (tenant_id, toYYYYMM(timestamp))
@@ -349,6 +350,7 @@ CREATE TABLE IF NOT EXISTS logs (
     stack_trace  String DEFAULT '',
     exchange_id  String DEFAULT '',
     mdc          Map(String, String) DEFAULT map(),
+    insert_id    UUID DEFAULT generateUUIDv4(),
 
     INDEX idx_msg   message TYPE ngrambf_v1(3, 256, 2, 0) GRANULARITY 4,
     INDEX idx_stack stack_trace TYPE ngrambf_v1(3, 256, 2, 0) GRANULARITY 4,
@@ -398,3 +400,12 @@ CREATE TABLE IF NOT EXISTS route_catalog (
 )
 ENGINE = ReplacingMergeTree(last_seen)
 ORDER BY (tenant_id, environment, application_id, route_id);
+
+-- insert_id tiebreak for keyset pagination (fixes same-millisecond cursor collision).
+-- IF NOT EXISTS on ADD COLUMN is idempotent. MATERIALIZE COLUMN is a background mutation,
+-- effectively a no-op once all parts are already materialized.
+ALTER TABLE logs ADD COLUMN IF NOT EXISTS insert_id UUID DEFAULT generateUUIDv4();
+ALTER TABLE logs MATERIALIZE COLUMN insert_id;
+
+ALTER TABLE agent_events ADD COLUMN IF NOT EXISTS insert_id UUID DEFAULT generateUUIDv4();
+ALTER TABLE agent_events MATERIALIZE COLUMN insert_id;