Integration test for cmd/ingestion full-import pipeline

[koinsaari]

Goal

End-to-end integration test for cmd/ingestion full-import against a real Postgres/PostGIS container. The walking skeleton (#57) has no test coverage of the wired pipeline today.

Tracking under #10.

Scope

• Build-tag integration, consistent with other integration tests in this repo (per CLAUDE.md).
• Use testcontainers-go for Postgres/PostGIS, consistent with internal/testhelpers/.
• Use a tiny fixture .osm.pbf (a handful of nodes, mix of POIs and non-POIs) checked into the repo under testdata/.
• Run the full pipeline (osm.StreamNodes → Evaluate → TransformNode → UpsertBatch).
• Assert:
  • Only nodes matching osm.Evaluate land in places.
  • Place.Geometry, Tags, Rank are populated correctly for a known fixture node.
  • Re-running full-import on the same fixture is a no-op on row count (idempotency via (osm_id, osm_type) conflict key).

Out of scope

• diff-sync testing (covered in its own issue).
• Performance / load testing.

Acceptance

• New file under cmd/ingestion/ (e.g. full_import_integration_test.go) with the integration build tag.
• go test -tags integration ./cmd/ingestion/... passes locally and in CI.
• Fixture .osm.pbf is small (< 50 KB) and version-controlled.