Accounting: categorize register transactions from Buildium GL lines

partymap mode now also resolves each Buildium transaction's dominant
income/expense account (from its Journal lines) to a local category, staged
alongside the party. Used to backfill accounting.transactions.category on the
materialized bank register. Applied to Village Woods.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

supabase/migrations/20260615190000_buildium_party_map_category.sql

@@ -0,0 +1,7 @@
+-- Extend the payee/payor staging table to also carry the resolved income/expense
+-- category (the dominant Journal line of each Buildium GL transaction) and its
+-- local account, used to backfill accounting.transactions.category on the
+-- materialized bank register of imported-GL companies.
+alter table accounting.buildium_party_map
+  add column if not exists category_name text,
+  add column if not exists coa_account_id uuid;