fix(auth): handle production login errors via Astro ActionError

[saifulalomdev]

📝 Description

This PR addresses a critical production routing issue where failed authentication credentials threw generic JavaScript errors, disrupting client-side notification routing. It transitions the validation failure mechanism to a secure, explicit Astro error schema.

Key Changes:

• Production Error Handling: Replaced the generic throw new Error() check with an explicit Astro ActionError object.
• Security & Categorization: Configured the error state with the formal UNAUTHORIZED runtime code block to ensure predictable status headers and client-side handling under Cloudflare production edge deployments.

Fixes # (issue number)

🧪 Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor / Chore (codebase maintenance or optimization)

🛠️ How Has This Been Tested?

• Verified credential rejection states locally within development runtime configurations.

• Inspected execution logs to guarantee that client-side useAction catch blocks handle the descriptive string error message accurately without swallowing the response object.

• Unit/Integration tests added/passed

• Local manual edge verification successful

📸 Screenshots / Diffs (if applicable)

Modified File: src/modules/auth/auth.actions.ts

✅ Checklist

• My code follows the brutalist/minimal style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new typescript compiler or linter errors