Revert: drop certificate_number column from property table

We decided the EPC certificate number only needs to travel through the
address2uprn pipeline internally and doesn't need a persisted column
on property (reverts #362).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/db/migrations/0265_drop_property_certificate_number.sql

@@ -0,0 +1 @@
+ALTER TABLE "property" DROP COLUMN "certificate_number";

src/app/db/migrations/meta/_journal.json

@@ -1849,6 +1849,13 @@
       "when": 1783430551377,
       "tag": "0264_yummy_master_chief",
       "breakpoints": true
+    },
+    {
+      "idx": 265,
+      "version": "7",
+      "when": 1783433702298,
+      "tag": "0265_drop_property_certificate_number",
+      "breakpoints": true
     }
   ]
 }

src/app/db/schema/property.ts

@@ -117,7 +117,6 @@ export const property = pgTable(
 
     creationStatus: propertyCreationStatusEnum("creation_status").notNull(),
     uprn: bigint("uprn", { mode: "bigint" }),
-    certificateNumber: text("certificate_number"),
 
     landlordPropertyId: text("landlord_property_id"),
     buildingReferenceNumber: bigint("building_reference_number", {