feat(deploy): docker image, caddy, compose, e2e script

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMHQTtnQtQqL8muAXHr9kd

Dockerfile

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+# syntax=docker/dockerfile:1
+
+# 1) build web (React/Vite SPA)
+FROM node:22-alpine AS web
+WORKDIR /web
+COPY web/package.json web/package-lock.json ./
+RUN npm ci
+COPY web/ ./
+RUN npm run build
+
+# 2) build go (embed web build via internal/httpapi/webdist)
+FROM golang:1.24-alpine AS go
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+# overwrite the committed webdist stub with the real SPA build
+RUN rm -rf ./internal/httpapi/webdist
+COPY --from=web /web/dist ./internal/httpapi/webdist
+RUN CGO_ENABLED=0 go build -trimpath -o /out/server ./cmd/server
+
+# 3) runtime
+FROM alpine:3.20
+RUN apk add --no-cache ca-certificates
+WORKDIR /app
+COPY --from=go /out/server /app/server
+COPY migrations /app/migrations
+EXPOSE 8080
+ENTRYPOINT ["/app/server"]