fix: harden Redis client timeouts and correct userid column bugs

Redis client had a 35s worst-case stall (10s read/write timeout x3
retries) on a single call, which under concurrent load exhausted the
connection pool and cascaded into a full outage. Timeouts and retries
are now tight enough that a degraded Redis fails fast instead of
tying up pooled connections.

Also fixes two userid/appuserid column mix-ups in delivery queries
(deliveryController.go, domain/delivery.go) and points the Dockerfile
build at main.go explicitly.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

db/connect.go

@@ -183,18 +183,23 @@ func InitRedis() {
 		DB:       0,
 
 		// ✅ TIMEOUTS (VERY IMPORTANT)
-		DialTimeout:  10 * time.Second,
-		ReadTimeout:  10 * time.Second,
-		WriteTimeout: 10 * time.Second,
+		// Kept short so a slow/degraded Redis fails fast instead of tying up a
+		// pooled connection for tens of seconds. A previous config (10s x3 retries)
+		// let a single stuck call hold a connection for ~35s, which under concurrent
+		// load exhausted the pool and cascaded into a cluster-wide outage.
+		DialTimeout:  5 * time.Second,
+		ReadTimeout:  3 * time.Second,
+		WriteTimeout: 3 * time.Second,
 
 		// ✅ POOL
 		PoolSize:     50,
 		MinIdleConns: 10,
+		PoolTimeout:  4 * time.Second,
 
 		// ✅ RETRIES
-		MaxRetries:      3,
-		MinRetryBackoff: 500 * time.Millisecond,
-		MaxRetryBackoff: 2 * time.Second,
+		MaxRetries:      1,
+		MinRetryBackoff: 100 * time.Millisecond,
+		MaxRetryBackoff: 500 * time.Millisecond,
 	})
 
 	maxRetries := 5