Move ckpool logs and kamado-api DB to persisted volumes

The default LOGDIR and DB_PATH both pointed at ephemeral container
paths, so a service restart wiped the pool's users/workers state,
its block history, and kamado-api's hashrate chart.

- LOGDIR: /var/log/ckpool -> /root/.ckpool/logs (ckpool volume).
  Persists pool/pool.status, users/, workers/, and daily logs.
- DB_PATH: default /var/lib/kamado/kamado.db
  -> /root/.kamado/data/kamado.db (main volume).
  Persists blocks, hashrate_samples, and the kv table that holds
  cumulative pool work.

CKPOOL_LOGFILE follows LOGDIR so kamado-api's log-tailer keeps
picking up ckpool's block-solve lines.

docker_entrypoint.sh

@@ -62,7 +62,10 @@ TLS_PORT=$(q '.tls.port // 3334')
 # never credits it a satoshi.
 export POOL_BTCADDRESS="${SELFTEST_ADDRESS}"
 
-export LOGDIR=/var/log/ckpool
+# LOGDIR lives on the ckpool data volume so ckpool's own state files
+# (users/, workers/, pool/pool.status, daily log files) survive restart.
+# SOCKET_DIR is ephemeral — sockets are re-created on each start.
+export LOGDIR=/root/.ckpool/logs
 export SOCKET_DIR=/run/ckpool
 export BITCOIN_NOTIFY=true
 # ckpool itself doesn't use ZMQ in this build — zmqblock is stripped
@@ -101,9 +104,14 @@ echo "kamado-entrypoint: starting ckpool (solo, ${BITCOIND_VARIANT}) on port ${S
 /usr/local/bin/ckpool --btcsolo --config "${CONF}" --sockdir "${SOCKET_DIR}" --log-shares &
 CKPOOL_PID=$!
 
+# DB_PATH must live on the persisted main volume; the default
+# /var/lib/kamado/kamado.db is ephemeral container storage.
+KAMADO_DATA_DIR=/root/.kamado/data
+mkdir -p "${KAMADO_DATA_DIR}"
 export LISTEN_ADDR=":8080"
 export CKPOOL_SOCKDIR="${SOCKET_DIR}"
 export CKPOOL_LOGFILE="${LOGDIR}/ckpool.log"
+export DB_PATH="${KAMADO_DATA_DIR}/kamado.db"
 export BITCOIN_RPC_URL="http://${BITCOIN_RPC_HOST}:${BITCOIN_RPC_PORT}"
 export POLL_INTERVAL=5s
 export KAMADO_LOG_LEVEL="${LOG_LEVEL}"