Adds two parallel DocType families that don't touch the existing
`Property tax return` family:
- Property Tax Return AI (parent + 10 children): cabinet-verified port
of the property-tax formulas (501/503/504 mirrors, 506=1, 509.1/509.2,
511.x) with parity 3/3 vs. the original.
- Property Tax Return AI Fill (parent + 10 children): same formulas plus
auto-fill from ERPNext Asset records. On form open the seeded grid is
populated from the single Company's Assets, routed by
`taxable_asset_type` (→ elavə 2 rows 1.1–1.6, 2–5) and
`tax_exempt_tax_article` (→ elavə 1 rows by article-code regex).
Residuals at year boundaries come from Depreciation Schedule;
Company.date_of_establishment drives 507 ayla when il_erzinde=1.
Coverage: 16/16 smoke (seeding + formulas + 11 autofill scenarios) and
3/3 parity vs. original Property tax return pass.
Also adds .etaxes_notes/cabinet_internals.md (sanitised cabinet probe
notes) and gitignores .etaxes_notes/scratch/ which holds live JWTs and
HAR-like dumps.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
