🗂️ refactor: organize Dockerfiles into docker/ directory and update all references

docker/Dockerfile.prod

@@ -0,0 +1,37 @@
+# DanceLessonsCoach Production Docker Image
+# ⚠️ DEVELOPMENT ONLY - This file uses 'latest' tag for local testing
+# ⚠️ CI/CD generates the correct Dockerfile.prod with proper dependency hash
+# ⚠️ For production use, see the CI/CD workflow which generates the correct file
+
+# Use the build cache image as base (latest for local dev only)
+FROM gitea.arcodange.lab/arcodange/dance-lessons-coach-build-cache:latest AS builder
+
+# Final minimal image
+FROM alpine:3.18
+
+WORKDIR /app
+
+# Install minimal dependencies
+RUN apk add --no-cache ca-certificates tzdata
+
+# Copy binary from builder
+COPY --from=builder /workspace/dance-lessons-coach /app/dance-lessons-coach
+
+# Copy configuration
+COPY config.yaml /app/config.yaml
+
+# Set permissions
+RUN chmod +x /app/dance-lessons-coach
+
+# Set timezone
+ENV TZ=UTC
+
+# Expose port
+EXPOSE 8080
+
+# Health check
+HEALTHCHECK --interval=30s --timeout=3s \
+    CMD wget -q --spider http://localhost:8080/api/health || exit 1
+
+# Entry point
+ENTRYPOINT ["/app/dance-lessons-coach"]