Add full monorepo: virtual-banker, backend, frontend, docs, scripts, deployment

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/database/migrations/0008_add_iso_timestamps.down.sql

@@ -0,0 +1,18 @@
+-- Rollback migration: Remove ISO timestamp columns
+
+-- Drop triggers
+DROP TRIGGER IF EXISTS trigger_transactions_timestamp_iso ON transactions;
+DROP TRIGGER IF EXISTS trigger_blocks_timestamp_iso ON blocks;
+
+-- Drop functions
+DROP FUNCTION IF EXISTS update_transaction_timestamp_iso();
+DROP FUNCTION IF EXISTS update_timestamp_iso();
+
+-- Drop indexes
+DROP INDEX IF EXISTS idx_transactions_chain_timestamp_iso;
+DROP INDEX IF EXISTS idx_blocks_chain_timestamp_iso;
+
+-- Drop columns
+ALTER TABLE transactions DROP COLUMN IF EXISTS timestamp_iso;
+ALTER TABLE blocks DROP COLUMN IF EXISTS timestamp_iso;
+