Add _meta column to greenlight_pr_state

- Add sql/003 migration adding `_meta Tuple(bucket, key)` to
  misc.greenlight_pr_state via ALTER TABLE ... ADD COLUMN IF NOT EXISTS
- Position `_meta` after `version` so it is the last ordinary column,
  before the MATERIALIZED `_inserted_at`

Notes:
The clickhouse-replicator-s3 ingestion path (general_adapter) inserts
positionally with `SELECT *, (bucket, key) AS _meta`, so the S3
provenance tuple must be the trailing ordinary column for positional
alignment to hold. Applied manually to the live table (clee2000/huydhn);
there is no automated migration runner.

Signed-off-by: Jean Schmidt <contato@jschmidt.me>

Author: jeanschmidt

greenlight/sql/003_alter_greenlight_pr_state_add_meta.sql

@@ -0,0 +1,6 @@
+-- Add the S3 provenance column the clickhouse-replicator-s3 ingestion path needs:
+-- general_adapter inserts positionally (`SELECT *, (bucket, key) AS _meta`), so
+-- `_meta` must be the last ordinary column, before the MATERIALIZED `_inserted_at`.
+-- Applied manually to the live table by clee2000/huydhn (no automated migration).
+ALTER TABLE misc.greenlight_pr_state
+ADD COLUMN IF NOT EXISTS `_meta` Tuple(bucket String, key String) AFTER `version`