Implement the xtask gen-schema binary at xtask/src/bin/gen_schema.rs that
derives JSON Schema Draft 2020-12 from the Rust ExtractionResult type via
the schemars crate.
Changes:
- Add stable key sorting (sort_keys_recursive) for byte-identical output
- Set $id to stable URL: https://pdftract.com/schema/v1.0/pdftract.schema.json
- Set title to "pdftract Output v1.0"
- Add cargo alias `gen-schema` for convenient invocation
- Emit schema to docs/schema/v1.0/pdftract.schema.json
The schema is generated from the Rust types with schemars derives, ensuring
the JSON schema is always in sync with the source types.
Acceptance criteria:
- cargo gen-schema regenerates docs/schema/v1.0/pdftract.schema.json
- Generated schema validates against JSON Schema Draft 2020-12
- Schema $id is the stable URL
- Title is "pdftract Output v1.0"
- Stable ordering: regenerating twice produces byte-identical output
- All expected types appear in $defs (BlockJson, SpanJson, PageResult, etc.)
Note: page_type and confidence_source enums are not yet implemented in the
Rust types (marked as TODO in schema/mod.rs). These will be added by sibling
beads pdftract-1ob and pdftract-1f8we respectively.
Closes: pdftract-5nv9h