feat: enable document orientation detection for scanned PDFs

- Enable PP-StructureV3's use_doc_orientation_classify feature
- Detect rotation angle from doc_preprocessor_res.angle
- Swap page dimensions (width <-> height) for 90°/270° rotations
- Output PDF now correctly displays landscape-scanned content

Also includes:
- Archive completed openspec proposals
- Add simplify-frontend-ocr-config proposal (pending)
- Code cleanup and frontend simplification

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

openspec/changes/archive/2025-12-11-simple-text-positioning/tasks.md

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+# Tasks: Simple Text Positioning
+
+## Phase 1: Core Implementation
+
+- [x] Create `TextRegionRenderer` class in `app/services/text_region_renderer.py`
+  - [x] Implement `calculate_rotation()` from bbox quadrilateral
+  - [x] Implement `estimate_font_size()` from bbox height
+  - [x] Implement `render_text_region()` main method
+  - [x] Handle coordinate system transformation (OCR → PDF)
+
+## Phase 2: Integration
+
+- [x] Add `simple_text_positioning_enabled` config option
+- [x] Modify `PDFGeneratorService._generate_ocr_track_pdf()` to use `TextRegionRenderer`
+- [x] Ensure raw OCR regions are loaded correctly via `load_raw_ocr_regions()`
+
+## Phase 3: Image/Chart/Formula Support
+
+- [x] Add image element type detection (`figure`, `image`, `chart`, `seal`, `formula`)
+- [x] Render image elements from UnifiedDocument to PDF
+- [x] Handle image path resolution (result_dir, imgs/ subdirectory)
+- [x] Coordinate transformation for image placement
+
+## Phase 4: Text Straightening & Overlap Avoidance
+
+- [x] Add rotation straightening threshold (default 10°)
+  - Small rotation angles (< 10°) are treated as 0° for clean output
+  - Only significant rotations (e.g., 90°) are preserved
+- [x] Add IoA (Intersection over Area) overlap detection
+  - IoA threshold default 0.3 (30% overlap triggers skip)
+  - Text regions overlapping with images/charts are skipped
+- [x] Collect exclusion zones from image elements
+- [x] Pass exclusion zones to text renderer
+
+## Phase 5: Chart Axis Label Deduplication
+
+- [x] Add `is_axis_label()` method to detect axis labels
+  - Y-axis: Vertical text immediately left of chart
+  - X-axis: Horizontal text immediately below chart
+- [x] Add `is_near_zone()` method for proximity checking
+- [x] Position-aware deduplication in `render_text_region()`
+  - Collect texts inside zones + axis labels
+  - Skip matching text only if near zone or is axis label
+  - Preserve matching text far from zones (e.g., table values)
+- [x] Test results:
+  - "Temperature, C" and "Syringe Thaw Time, Minutes" correctly skipped
+  - Table values like "10" at top of page correctly rendered
+  - Page 2: 128/148 text regions rendered (12 overlap + 8 dedupe)
+
+## Phase 6: Testing
+
+- [x] Test with scan.pdf task (064e2d67-338c-4e54-b005-204c3b76fe63)
+  - Page 2: Chart image rendered, axis labels deduplicated
+  - PDF is searchable and selectable
+  - Text is properly straightened (no skew artifacts)
+- [ ] Compare output quality vs original scan visually
+- [ ] Test with documents containing seals/formulas