fix: restore ALTER INDEX ... ATTACH PARTITION with indices and constraints

[siriusfreak]

Fixes the partitioned-index half of #1093.

The problem

parseDump classifies dump lines by prefix. ALTER INDEX … ATTACH PARTITION matches none of the special cases — it starts with ALTER INDEX, not ALTER TABLE or CREATE INDEX — so it falls through to default and lands in the filtered segment. That segment is restored before indicesAndConstraints, where the parent index is created, so every attach fails with relation does not exist. The error is bucketed as ignorable and never retried, and the parent index stays indisvalid = false on the target.

Why it is worth fixing beyond the index

An invalid index is not usable as a constraint either, so a partitioned table's PRIMARY KEY does not exist on the target. That means:

• no replica identity for UPDATE/DELETE;
• no conflict target for INSERT — buildOnConflictQuery returns "" when there are no primary key columns;
• with strict_mode: false, those changes are dropped and the checkpoint advanced.

So a load that reports success leaves a table that silently stops replicating. We hit this on a JFrog Artifactory schema, where jfbus_events is partitioned; the only trace was one line of restore: N errors ignored.

The change

Route the statement into indicesAndConstraints, which puts it after the CREATE INDEX it depends on — pg_dump already emits the parent index first, so ordering within the segment is preserved. Kept narrow: no change to error classification, though as noted on the issue that is the reason both this and the extension case were invisible, and I would be glad to follow up separately if you want it.

Verification

Unit test added alongside the existing parseDump cases: it asserts the table attachment stays in filtered, the index attachment moves to indicesAndConstraints, and that it lands after the parent CREATE INDEX.

End to end, against the reproduction from #1093 — a partitioned table with a primary key and a secondary index, snapshotted into an empty target:

	before	after
ignored errors	5, incl. 4 × does not exist	1, no does not exist
pg_index WHERE NOT indisvalid	jfbus_events_pkey, jfbus_events_topic_partition_event_id	empty
rows	5000	5000

go test ./pkg/snapshot/... passes.