test: add E2E test suite for Phase 2 reconciliation features (#919)

Add 13 integration tests covering all Phase 2 features:

Balance assertion via gRPC:
- Balanced case (PASSED status, no imbalance event)
- Imbalanced case (FAILED status, imbalance event, trend tracking)
- Invalid input validation (bad balance, bad UUID)
- Run-linked assertion

Kafka event publishing:
- Full pipeline with event verification
- Noop publisher mode (disabled Kafka)

Full pipeline with valuation:
- Detect -> value -> finalize lifecycle
- Valuation engine failure and retry
- Multi-instrument reconciliation (3 instruments, 2 variances)

PAUSE/RESUME control actions:
- Full pause/resume cycle with checkpoint preservation
- Invalid state transitions (pause pending, resume pending, resume cancelled)
- Cancel from paused state

Cross-feature integration:
- Pipeline + assertion + events combined

Infrastructure changes:
- Add last_completed_phase column to settlement_run DDL
- Add LastCompletedPhase field to GORM entity and mappings
- Set MaxOpenConns(1) to prevent search_path loss on pool connections

Co-authored-by: Ben Coombs <bjcoombs@users.noreply.github.com>

Author: bjcoombs

tests/reconciliation-e2e/infra_test.go

@@ -80,6 +80,13 @@ func setupE2EInfra(t *testing.T) *e2eTestInfra {
 	infra.db = db
 	infra.cleanup = cleanup
 
+	// Limit the connection pool to 1 so all operations (including concurrent
+	// errgroup goroutines) share the same connection with search_path set.
+	// Without this, new pool connections would miss the tenant search_path.
+	sqlDB, err := db.DB()
+	require.NoError(t, err)
+	sqlDB.SetMaxOpenConns(1)
+
 	// Set up tenant schema and apply migrations
 	tc := testdb.SetupTenantSchema(t, db, "e2e_recon_tenant")
 	t.Cleanup(tc.Cleanup)
@@ -221,6 +228,7 @@ func applyMigrations(t *testing.T, db *gorm.DB, _ tenant.TenantID) {
 			completed_at timestamptz NULL,
 			variance_count integer NOT NULL DEFAULT 0,
 			failure_reason text NULL,
+			last_completed_phase character varying(30) NULL,
 			attributes jsonb NULL,
 			version bigint NOT NULL DEFAULT 1,
 			PRIMARY KEY (id)