Fix FromAsCasing warnings in all Dockerfiles

[Copilot]

Docker BuildKit was emitting FromAsCasing warnings during image builds due to inconsistent keyword casing in multi-stage build declarations.

Changes

• backend/Dockerfile: Updated 4 stage declarations (base, development, testing, production)
• backend/Dockerfile.prod: Updated builder stage declaration
• backend/queue.dockerfile.prod: Updated builder stage declaration
• react-frontend/Dockerfile: Updated 5 stage declarations (base, development, testing, build, production)
• react-frontend/Dockerfile.prod: Updated builder stage declaration

All instances changed from lowercase as to uppercase AS to match the FROM keyword:

# Before
FROM python:3.10-slim-buster as base

# After
FROM python:3.10-slim-buster AS base

Total: 12 instances across 5 files. Eliminates all build warnings while maintaining functional equivalence.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Resolve any warning related to the docker image built</issue_title>
<issue_description>There are warnings during the Docker image build process, such as the 'FromAsCasing' warning (e.g., 'FROM ... as ...' should use lowercase 'as').

Please review all Dockerfiles and resolve any build warnings, including but not limited to:

• 'FromAsCasing' (use lowercase 'as' in multi-stage builds)
• Any other Docker build warnings or best practice violations

This will ensure clean builds and better maintainability. Refer to the latest Docker best practices for multi-stage builds and syntax.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Resolve any warning related to the docker image built #8

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[mnaimfaizy]

@copilot I think you have missed the other dockerfiles like queue.dockerfile or queue.dockerfile.prod.

[Copilot]

@copilot I think you have missed the other dockerfiles like queue.dockerfile or queue.dockerfile.prod.

You're right! I've now fixed the FromAsCasing warning in backend/queue.dockerfile.prod (line 5: changed as builder to AS builder).

The backend/queue.dockerfile doesn't have multi-stage builds, so no changes were needed there.

All 6 Dockerfiles have been checked, and all FromAsCasing warnings are now resolved (12 total instances fixed across 5 files).

Commit: 423a92d

[mnaimfaizy]

@copilot you have updated the queue.dockerfile.prod but the queue.dockerfile is still not updated correctly. Please apply the changes to that file as well if needed.

[Copilot]

@copilot you have updated the queue.dockerfile.prod but the queue.dockerfile is still not updated correctly. Please apply the changes to that file as well if needed.

The queue.dockerfile doesn't require any changes because it's a single-stage Dockerfile without any multi-stage build declarations (no FROM ... AS/as statements).

I verified this by:

1. Checking the file content - it only has FROM python:3.10-slim-buster on line 1 (no stage name)
2. Building the file - no warnings are generated

Only queue.dockerfile.prod needed fixing (which was done in commit 423a92d) because it has multi-stage builds.

All Dockerfiles with multi-stage builds have been corrected to use uppercase AS (the Docker BuildKit recommended practice), and all are now warning-free.