chore(test): the DB lane runs on every core — each pytest-xdist worker gets its own database

frontend/src/lib/gates.snapshot.json

@@ -1232,6 +1232,7 @@
       "      POSTGRES_DB: siftlode_test",
       "    tmpfs:",
       "      - /var/lib/postgresql/data  # ephemeral + fast; the schema is rebuilt per run",
+      "    command: [\"postgres\", \"-c\", \"max_connections=300\"]",
       "    healthcheck:",
       "      test: [\"CMD-SHELL\", \"pg_isready -U siftlode -d siftlode_test\"]",
       "      interval: 1s",
@@ -1250,7 +1251,7 @@
       "    volumes:",
       "      - ./:/app",
       "    working_dir: /app",
-      "    command: [\"python\", \"-m\", \"pytest\"]"
+      "    command: [\"python\", \"-m\", \"pytest\", \"-n\", \"auto\"]"
     ],
     "frontend/.prettierignore": [
       "dist",