## [2026-03-07] JSON Schema for AviaNZ .data Files
**New feature:** Added JSON Schema (Draft 2020-12) for validating AviaNZ .data annotation files.
**Added:**
- `db/avianz_data_schema.json` — Comprehensive schema for .data file format
**Schema coverage:**
- Root array with metadata object first, then segment arrays
- Meta object with `Operator`, `Reviewer`, `Duration` (optional, allows extra fields)
- Segment array: 5-element tuple `[starttime, endtime, freq_low, freq_high, labels]`
- Label object with required `species` and `certainty` (0-100)
- Optional fields: `filter`, `calltype`, `comment` (max 140 chars)
- Additional properties allowed on all objects (extensibility)
- Pattern constraint: `species` must not contain `>` separator

**Validation tests:**
- Missing required fields caught
- Certainty range (0-100) enforced
- Comment length (max 140) enforced
- Minimal valid files accepted