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

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

backend/database/migrations/0009_add_link_token.down.sql

@@ -0,0 +1,7 @@
+-- Rollback: Remove LINK token from tokens table
+-- Note: This only removes if it matches the exact address
+
+DELETE FROM tokens
+WHERE chain_id = 138
+  AND address = '0x514910771AF9Ca656af840dff83E8264EcF986CA';
+