Fix legacy view test: create builder before installing legacy view

UnifiedMatrixBuilder.__init__ calls create_or_replace_views, which
overwrites any previously installed view. The test was installing the
legacy view first, then creating a builder that immediately replaced it
with the current view (containing reform_id). Fix by creating the
builder first, then installing the legacy view, and clearing the cached
column metadata so the builder re-introspects the legacy schema.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: baogorek

policyengine_us_data/tests/test_calibration/test_unified_matrix_builder.py

@@ -275,9 +275,10 @@ def test_inactive_targets_are_excluded(self):
         self.assertEqual(float(baseline_rows.iloc[0]["value"]), 10000.0)
 
     def test_legacy_target_overview_without_reform_id(self):
+        b = self._make_builder()
         _create_legacy_target_overview(self.engine)
         try:
-            b = self._make_builder()
+            b._target_overview_columns = None
             df = b._query_targets({"domain_variables": ["aca_ptc"]})
             self.assertGreater(len(df), 0)
             self.assertIn("reform_id", df.columns)