Add certificate_number column to property table

The address2uprn lookup already returns the EPC certificate number
alongside the UPRN, but only the UPRN is persisted today. This adds
a nullable column so a follow-up change can start saving it.

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

src/app/db/migrations/0263_add_property_certificate_number.sql

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

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

@@ -1835,6 +1835,13 @@
       "when": 1783420235209,
       "tag": "0262_wandering_nocturne",
       "breakpoints": true
+    },
+    {
+      "idx": 263,
+      "version": "7",
+      "when": 1783425021407,
+      "tag": "0263_add_property_certificate_number",
+      "breakpoints": true
     }
   ]
 }

src/app/db/schema/property.ts

@@ -117,6 +117,7 @@ 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", {