Add weekly build workflow to ensure regular builds even during quiet periods

[Copilot]

This PR adds a new GitHub Actions workflow that runs builds automatically once per week, ensuring that builds are executed regularly even when there are no recent changes to the main branch.

Changes Made

• New workflow file: .github/workflows/weekly-build.yml
• Schedule: Runs every Sunday at midnight UTC using cron expression '0 0 * * 0'
• Manual trigger: Includes workflow_dispatch for testing purposes
• Build matrix: Uses identical configuration to the existing build.yml workflow
• Artifact naming: Weekly build artifacts are suffixed with -weekly to distinguish them from push-triggered builds

Rationale

The existing build.yml workflow only runs when code is pushed to main or release branches. During periods of low activity, this could mean builds don't run for extended periods, potentially missing issues with dependencies, toolchain updates, or other environmental changes.

This weekly build ensures:

• Regular validation of the build process
• Early detection of dependency or environment issues
• Consistent artifact generation for downstream processes
• Maintained build confidence during quiet development periods

Testing

The workflow can be manually triggered via the GitHub Actions UI for immediate testing. The scheduled execution will begin automatically according to the cron schedule.

Fixes #225.

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[eleanorjboyd]

@copilot please update to add the new weekly run to the existing azure yml instead of making a new one

[Copilot]

@copilot please update to add the new weekly run to the existing azure yml instead of making a new one

I've updated the implementation as requested. Removed the GitHub Actions weekly workflow and added the weekly schedule to the existing Azure pipeline (pre-release.yml) instead. The weekly build now runs every Sunday at midnight UTC using Azure's schedules configuration. Changes made in commit 4a0a55a.