This commit completes Phase 5.2.2 by integrating the pdfium-render path
into serve mode with runtime validation and feature propagation.
Changes:
- Propagate ocr and full-render features from CLI to pdftract-core
- Add full_render parameter to serve mode ExtractParams
- Implement runtime validation in build_options():
* Returns BadRequest if full_render requested but PDFium unavailable
* Falls back to direct compositing if feature not compiled
- Update all three serve handlers to handle Result from build_options()
Acceptance Criteria:
✅ cargo build --features ocr,serve,full-render succeeds
✅ cargo build --features ocr,serve (no full-render) succeeds
✅ Runtime fallback: full_render=true with feature absent uses direct path
Notes:
- Binary size CI gate (140 MB) requires separate CI infrastructure
- Soft-mask regression tests require separate fixture work
Refs: pdftract-4my
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>