fix: Dockerfile for library-only module with no cmd/ directory

tok has no main package or cmd/ directory. Change to build
verification only (go build ./...) and add tzdata for zoneinfo.

Author: Patel230

Dockerfile

@@ -1,16 +1,21 @@
 FROM golang:1.26.3-alpine AS builder
 
+RUN apk add --no-cache tzdata
+
 WORKDIR /src
 COPY go.mod go.sum ./
 RUN go mod download
 
 COPY . .
-ARG VERSION=dev
-RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w -X 'github.com/GrayCodeAI/tok/internal/version.Version=${VERSION}'" -o /tok ./cmd/tok/
+RUN CGO_ENABLED=0 go build -trimpath ./...
 
 FROM alpine:3.21
-RUN apk add --no-cache ca-certificates git
-COPY --from=builder /tok /usr/local/bin/tok
+RUN apk add --no-cache ca-certificates git tini && \
+    adduser -D -u 1000 tok
+
+COPY --from=builder /usr/share/zoneinfo /usr/share/zoneinfo
 
-ENTRYPOINT ["tok"]
-CMD ["--help"]
+USER tok
+WORKDIR /workspace
+ENTRYPOINT ["tini", "--"]
+CMD ["sleep", "infinity"]