fix: update Dockerfile and deployment workflow for amd64 compatibility

- Changed the Docker build platform in `deploy-web.yml` from linux/arm64 to linux/amd64 for consistent deployment.
- Specified the platform as linux/amd64 in all stages of `Dockerfile.lambda` to ensure compatibility with GitHub Actions runners and AWS Lambda.

Author: rithulkamesh

.github/workflows/deploy-web.yml

@@ -37,7 +37,7 @@ jobs:
           IMAGE_TAG: ${{ github.sha }}
         run: |
           cd web
-          docker buildx build --provenance=false --platform linux/arm64 \
+          docker buildx build --provenance=false --platform linux/amd64 \
             -t $ECR_REGISTRY/$ECR_REPOSITORY:$IMAGE_TAG \
             -t $ECR_REGISTRY/$ECR_REPOSITORY:latest \
             -f Dockerfile.lambda \

web/Dockerfile.lambda

@@ -2,8 +2,8 @@
 # Uses AWS Lambda Web Adapter to proxy Lambda invoke → HTTP on :3000
 # Non-AWS base images work because the adapter bundles the Runtime Interface Client.
 
-# Stage 1: install deps + build React SPA
-FROM oven/bun:1-alpine AS builder
+# Stage 1: install deps + build React SPA (explicit amd64 for GitHub Actions runner / Lambda)
+FROM --platform=linux/amd64 oven/bun:1-alpine AS builder
 WORKDIR /app
 COPY package.json bun.lock* ./
 RUN bun install --frozen-lockfile
@@ -17,13 +17,13 @@ ENV VITE_GOOGLE_CLIENT_ID=$VITE_GOOGLE_CLIENT_ID
 RUN bun run build
 
 # Stage 2: production deps only
-FROM oven/bun:1-alpine AS deps
+FROM --platform=linux/amd64 oven/bun:1-alpine AS deps
 WORKDIR /app
 COPY package.json bun.lock* ./
 RUN bun install --frozen-lockfile --production
 
 # Stage 3: Lambda runtime with web adapter
-FROM oven/bun:1-debian
+FROM --platform=linux/amd64 oven/bun:1-debian
 RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates && rm -rf /var/lib/apt/lists/*
 
 # Install Lambda Web Adapter (includes Runtime Interface Client for non-AWS base images)