Create resend email templates test with both React/raw-HTML templates

[afrinxnahar]

🎯 Problem Statement
Transactional mails sent via Resend currently lack standardized templates. Templates should be tested for both React-based and HTML templates and finalize one version at the end to follow.

💡 Proposed Solution

• Create a templating strategy both for React-based templates and raw HTML templates.
• Implement the following baseline templates for existing mails sent using resend (e.g welcome, reset-password, referral-invite etc)
• Finalize a template whether React or HTML for the future usecase
• Create all the templates under packages folder for best practices and import accordingly

🔄 Alternative Solutions

• Use only raw HTML templates (Just like now)
• Use an external transactional email templating service.

📊 Impact Assessment
User Impact: High, consistent emails improve UX.
Development Effort: Medium.
Priority: Medium.

🧪 Acceptance Criteria

• React/raw-HTML template pipelines exist.
• All listed templates render and pass unit tests.
• Resend integration tested (mocked or sandbox).