Added an e-filing JSON validator to India ITR Copilot

While hand-building a government-schema ITR-3 JSON for AY 2026-27, importing it into the tax department’s own e-filing utility, and correcting it against that utility’s re-export, I found several bugs that passed the project’s existing JSON-schema validation with zero errors the whole time: a capital-gains total that gets silently recomputed to zero on import if its detail schedule isn’t patched alongside it, an exemption that actually belongs in a different section than the schema implies, a table that needs exact rather than approximate equality with another schedule, a negative carry-forward value from a zero-deduction claim, and a contact field left at a skeleton default.

I turned those into a reusable module, a validator script with the concrete cross-schedule checks, and a test for each one, wired into the project’s existing filer workflow for anyone who wants the raw portal-schema JSON rather than just the data pack. Open as #2 .