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>

Dockerfile

@@ -4,7 +4,7 @@ FROM golang:1.24
 RUN mkdir /app
 ADD . /app/
 WORKDIR /app
-RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o server .
+RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o server main.go
 
 # Second Stage
 FROM alpine