Fix DHCP client unable to get IP and config not persisting

- Fixed verifyAssignment being too strict for new clients
- Fixed parseRequestedIP string conversion bug
- Fixed response sent to 0.0.0.0 instead of broadcast address
- Added SO_BROADCAST support for UDP socket
- Fixed session persistence after page refresh (localStorage)
- Added in-memory session store for auth middleware
- Added config reloader so DHCP server picks up web UI changes dynamically

Dockerfile

@@ -0,0 +1,21 @@
+FROM golang:1.21-alpine AS builder
+
+WORKDIR /app
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN CGO_ENABLED=1 GOOS=linux go build -a -installsuffix cgo -o main ./cmd
+
+FROM alpine:latest
+
+RUN apk --no-cache add ca-certificates
+
+WORKDIR /root/
+COPY --from=builder /app/main .
+COPY --from=builder /app/web ./web
+COPY --from=builder /app/configs ./configs
+
+EXPOSE 53/udp 67/udp 8080/tcp
+
+CMD ["./main", "-config", "configs/config.json"]