Closes the partial-coverage gap from batch 10. Adds two integration
tests in MigrationTests.cs:
- DedupeSqlCollapsesDuplicatesByLatestUpdatedAt_AZ357_AC2: seeds a
session-scoped temp table with intentional 4-column duplicates
(varying updated_at and id), runs the exact dedupe SQL from
migration 012, asserts only the expected rows survive (newest
updated_at wins; ties broken by largest id).
- NewUniqueConstraintExistsOnFourColumns_AZ357_AC2: queries
pg_indexes against the live DB to assert idx_tiles_unique_location
is a unique 4-column btree and excludes the version column.
Also wires Npgsql 9.0.2 into the integration-tests project, exposes
DB_CONNECTION_STRING + postgres healthcheck dependency to the test
container in docker-compose.tests.yml, and registers the new tests
in both smoke and full suites.
Implementation note: first attempt used CREATE TEMP TABLE
ON COMMIT DROP, which dropped the table immediately because each
Npgsql command runs in its own implicit transaction. Removed
ON COMMIT DROP — session-scoped temps are dropped on connection
close, which is what we want.
Co-authored-by: Cursor <cursoragent@cursor.com>