feat: create PDF layout restoration proposal

Create new OpenSpec change proposal to fix critical PDF generation issues:

**Problems Identified**:
1. Images never saved (empty _save_image implementation)
2. Image path mismatch (saved_path vs path lookup)
3. Tables never render (fake image dependency)
4. Text style completely lost (no font/color application)

**Solution Design**:
- Phase 1: Critical fixes (images, tables)
- Phase 2: Basic style preservation
- Phase 3: Advanced layout features
- Phase 4: Testing and optimization

**Key Improvements**:
- Implement actual image saving in pp_structure_enhanced
- Fix path resolution with fallback logic
- Use table's own bbox instead of fake images
- Track-specific rendering (rich for Direct, simple for OCR)
- Preserve StyleInfo (fonts, sizes, colors)

**Implementation Tasks**:
- 10 major task groups
- 4-week timeline
- No breaking changes
- Performance target: <10% overhead

Proposal validated: openspec validate pdf-layout-restoration ✓

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

openspec/changes/pdf-layout-restoration/proposal.md

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+# PDF Layout Restoration and Preservation
+
+## Problem
+Currently, the PDF generation from both OCR and Direct extraction tracks produces documents that are **severely degraded compared to the original**, with multiple critical issues:
+
+### 1. Images Never Appear
+- **OCR track**: `pp_structure_enhanced._save_image()` is an empty implementation (lines 262, 414), so detected images are never saved
+- **Direct track**: Image paths are saved as `content["saved_path"]` but converter looks for `content.get("path")`, causing a mismatch
+- **Result**: All PDFs are text-only, with no images whatsoever
+
+### 2. Tables Never Render
+- Table elements use fake `table_*.png` references that don't exist as actual files
+- `draw_table_region()` tries to find these non-existent images to get bbox coordinates
+- When images aren't found, table rendering is skipped entirely
+- **Result**: No tables appear in generated PDFs
+
+### 3. Text Layout is Broken
+- All text uses single `drawString()` call with entire block as one line
+- No line breaks, paragraph alignment, or text styling preserved
+- Direct track extracts `StyleInfo` but it's completely ignored during PDF generation
+- **Result**: Text appears as unformatted blocks at wrong positions
+
+### 4. Information Loss in Conversion
+- Direct track data gets converted to legacy OCR format, losing rich metadata
+- Span-level information (fonts, colors, styles) is discarded
+- Precise positioning information is reduced to simple bboxes
+
+## Solution
+Implement proper layout preservation for PDF generation:
+
+1. **Fix image handling**: Actually save images and use correct path references
+2. **Fix table rendering**: Use element's own bbox instead of looking for fake images
+3. **Preserve text formatting**: Use StyleInfo and span-level data for accurate rendering
+4. **Track-specific rendering**: Different approaches for OCR vs Direct tracks
+
+## Impact
+- **User Experience**: Output PDFs will actually be usable and readable
+- **Functionality**: Tables and images will finally appear in outputs
+- **Quality**: Direct track PDFs will closely match original formatting
+- **Performance**: No negative impact, possibly faster by avoiding unnecessary conversions
+
+## Tasks
+- Fix image saving and path references (Critical)
+- Fix table rendering using actual bbox data (Critical)
+- Implement track-specific PDF generation (Important)
+- Preserve text styling and formatting (Important)
+- Add span-level text rendering (Nice-to-have)
+
+## Deltas
+
+### result-export
+```delta
++ image_handling: Proper image saving and path resolution
++ table_rendering: Direct bbox usage for table positioning
++ text_formatting: StyleInfo preservation and application
++ track_specific_rendering: OCR vs Direct track differentiation
+```