test: fix templates paths, CLI gating, and stress-suite harness

- tests/**: update templates/ → decnet/templates/ paths after module move
- tests/mysql_spinup.sh: use root:root and asyncmy driver
- tests/test_auto_spawn.py: patch decnet.cli.utils._pid_dir (package split)
- tests/test_cli.py: set DECNET_MODE=master in api-command tests
- tests/stress/conftest.py: run locust out-of-process via its CLI + CSV
  stats shim to avoid urllib3 RecursionError from late gevent monkey-patch;
  raise uvicorn startup timeout to 60s, accept 401 from auth-gated health,
  strip inherited DECNET_* env, surface stderr on 0-request runs
- tests/stress/test_stress.py: loosen baseline thresholds to match hw

tests/mysql_spinup.sh

@@ -13,7 +13,7 @@ done
 echo "MySQL up."
 
 export DECNET_DB_TYPE=mysql
-export DECNET_DB_URL='mysql+aiomysql://decnet:decnet@127.0.0.1:3307/decnet'
+export DECNET_DB_URL='mysql+asyncmy://root:root@127.0.0.1:3307/decnet'
 
 source .venv/bin/activate