fix: add platform flags to Dockerfile for multi-arch builds

Ticket: WP-00000

Author: pranavjain97

Dockerfile

@@ -5,7 +5,7 @@
 # Pinned to specific SHA256 digest for supply chain security and deterministic builds
 # To update: podman pull node:22-alpine && podman inspect node:22-alpine --format '{{index .RepoDigests 0}}'
 # Last updated: 2025-10-24
-FROM node:22-alpine@sha256:d31216005bd330aa47f848822d4f269f6c79f0905b60cca1d87577149519daa6 AS builder
+FROM --platform=$BUILDPLATFORM node:22-alpine@sha256:d31216005bd330aa47f848822d4f269f6c79f0905b60cca1d87577149519daa6 AS builder
 
 # Set build-time variables for reproducibility
 ARG NODE_ENV=development
@@ -57,7 +57,7 @@ RUN npm run build
 # Production stage
 # Using node:22-alpine with OpenSSL 3.3.2+ to address CVE-2024-6119
 # Pinned to specific SHA256 digest for supply chain security and deterministic builds
-FROM node:22-alpine@sha256:d31216005bd330aa47f848822d4f269f6c79f0905b60cca1d87577149519daa6 AS production
+FROM --platform=$TARGETPLATFORM node:22-alpine@sha256:d31216005bd330aa47f848822d4f269f6c79f0905b60cca1d87577149519daa6 AS production
 
 # Declare build arguments in production stage
 ARG PORT=3081