[NA] [BE] feat: add task tiling and chapter summaries to cipx_session_analysis (#8154)

* [NA] [BE] feat: add task tiling and chapter summaries to cipx_session_analysis

The cost API's session analysis now emits two flat tilings per session — tasks
and chapters — and a summary per chapter, task and session. Adds the columns for
the three the create-table migration does not have.

Numbered 000121: the table creation landed on main as 000120, so the number this
was written against is taken.

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

* chore(migrations): renumber the session-analysis migration to 000122

000121 was free when this branch opened; 000121_add_aiu_nano_to_cipx_tables
has since merged to main. Different tables (cipx_spends / cipx_spend_blocks
vs cipx_session_analysis), so the clash was the number alone. The changeset
id moves with the filename.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Code <noreply@anthropic.com>

Author: andriidudar

apps/opik-backend/src/main/resources/liquibase/db-app-analytics/migrations/000122_add_tasks_to_cipx_session_analysis.sql

@@ -0,0 +1,16 @@
+--liquibase formatted sql
+--changeset andriid:000122_add_tasks_to_cipx_session_analysis
+--comment: Task tiling and chapter summaries for the cost API session analysis
+
+ALTER TABLE ${ANALYTICS_DB_DATABASE_NAME}.cipx_session_analysis ON CLUSTER '{cluster}'
+    ADD COLUMN IF NOT EXISTS `segments.summary`      Array(String),
+    ADD COLUMN IF NOT EXISTS `tasks.start_turn`      Array(UInt32),
+    ADD COLUMN IF NOT EXISTS `tasks.end_turn`        Array(UInt32),
+    ADD COLUMN IF NOT EXISTS `tasks.first_trace_id`  Array(FixedString(36)),
+    ADD COLUMN IF NOT EXISTS `tasks.last_trace_id`   Array(FixedString(36)),
+    ADD COLUMN IF NOT EXISTS `tasks.name`            Array(String),
+    ADD COLUMN IF NOT EXISTS `tasks.summary`         Array(String),
+    ADD COLUMN IF NOT EXISTS session_summary         String DEFAULT '';
+
+--rollback ALTER TABLE ${ANALYTICS_DB_DATABASE_NAME}.cipx_session_analysis ON CLUSTER '{cluster}' DROP COLUMN IF EXISTS `segments.summary`, DROP COLUMN IF EXISTS `tasks.start_turn`, DROP COLUMN IF EXISTS `tasks.end_turn`, DROP COLUMN IF EXISTS `tasks.first_trace_id`, DROP COLUMN IF EXISTS `tasks.last_trace_id`, DROP COLUMN IF EXISTS `tasks.name`, DROP COLUMN IF EXISTS `tasks.summary`, DROP COLUMN IF EXISTS session_summary;
+