Extract groombook/api from monorepo with CI workflow

- Add source code from apps/api
- Add packages/db and packages/types workspace dependencies
- Add GitHub Actions CI workflow (lint, typecheck, test, docker)
- Generate pnpm-lock.yaml
- Add .gitignore

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/db/migrations/0024_invoice_indexes.sql

@@ -0,0 +1,5 @@
+CREATE INDEX idx_invoices_client_id ON invoices(client_id);
+CREATE INDEX idx_invoices_status ON invoices(status);
+CREATE INDEX idx_invoices_created_at ON invoices(created_at);
+CREATE INDEX idx_invoice_line_items_invoice_id ON invoice_line_items(invoice_id);
+CREATE INDEX idx_invoice_tip_splits_invoice_id ON invoice_tip_splits(invoice_id);