GST Reporting Module Enhancement

My Prefix CRM instance already tracks contacts, deals and invoices, but its GST setup is missing a dedicated reporting layer. I need the existing Reporting/Analytics section modified so that GST is applied automatically to every relevant transaction and the data is then rolled up into compliant reports.

Scope of work
• Embed a “GST Setup” panel where I can define the default tax rate and any exemptions.
• Add logic that auto-applies GST to new and historical transactions, with overrides when required.
• Build an on-demand GST Report that summarises totals, input/output tax and balances for the selected period, ready for filing.
• Ensure figures reconcile with the current invoice data already stored in the system.
• Keep the UI consistent with the rest of Prefix CRM so users have a seamless experience.

Tech notes
The current stack is PHP/MySQL with jQuery on the front end. Clean, documented code is essential; ideally use migration scripts so the feature can be deployed safely to staging before it hits production.

Acceptance criteria
1. A user can toggle GST on or off for any product line and see the tax reflected instantly.
2. The new GST Report exports to CSV and PDF and matches manual calculations to the cent.
3. No existing reports or invoice screens break after the update.

Hand-off
Push code to our private Git repo and provide a short README explaining installation, tables affected and any cron jobs, if used. I will test on staging and sign off once the report balances against our latest quarter.