feat: add async modpack import support

scripts/migrations/003_modpack_import_jobs.sql

@@ -0,0 +1,13 @@
+CREATE TABLE modpack_import_jobs (
+    id SERIAL PRIMARY KEY,
+    status VARCHAR(50) NOT NULL DEFAULT 'pending',
+    progress INT NOT NULL DEFAULT 0,
+    error_message TEXT,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE TRIGGER set_timestamp_import_jobs
+BEFORE UPDATE ON modpack_import_jobs
+FOR EACH ROW
+EXECUTE FUNCTION trigger_set_timestamp();