fix: resolve E2E test failures and add Office direct extraction design

- Fix MySQL connection timeout by creating fresh DB session after OCR
- Fix /analyze endpoint attribute errors (detect vs analyze, metadata)
- Add processing_track field extraction to TaskDetailResponse
- Update E2E tests to use POST for /analyze endpoint
- Increase Office document timeout to 300s
- Add Section 2.4 tasks for Office document direct extraction
- Document Office → PDF → Direct track strategy in design.md

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

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

openspec/changes/dual-track-document-processing/design.md

@@ -118,11 +118,26 @@ def detect_track(file_path: Path) -> str:
         return "direct"
 
     if file_type in OFFICE_MIMES:
-        return "ocr"  # For now, may add direct Office support later
+        # Convert Office to PDF first, then analyze
+        pdf_path = convert_office_to_pdf(file_path)
+        return detect_track(pdf_path)  # Recursive call on PDF
 
     return "ocr"  # Default fallback
 ```
 
+**Office Document Processing Strategy**:
+1. Convert Office files (Word, PPT, Excel) to PDF using LibreOffice
+2. Analyze the resulting PDF for text extractability
+3. Route based on PDF analysis:
+   - Text-based PDF → Direct track (faster, more accurate)
+   - Image-based PDF → OCR track (for scanned content in Office docs)
+
+This approach ensures:
+- Consistent processing pipeline (all documents become PDF first)
+- Optimal routing based on actual content
+- Significant performance improvement for editable Office documents
+- Better layout preservation (no OCR errors on text content)
+
 ### Decision 5: GPU Memory Management
 **What**: Implement dynamic batch sizing and model caching for RTX 4060 8GB
 
@@ -221,7 +236,13 @@ def get_model(model_type: str):
   - A: No, adds complexity with minimal benefit. Document-level is sufficient.
 
 - Q: How to handle Office documents?
-  - A: OCR track initially, consider python-docx/openpyxl later if needed.
+  - A: Convert to PDF using LibreOffice, then analyze the PDF for text extractability.
+    - Text-based PDF → Direct track (editable Office docs produce text PDFs)
+    - Image-based PDF → OCR track (rare case of scanned content in Office)
+  - This approach provides:
+    - 10x+ faster processing for typical Office documents
+    - Better layout preservation (no OCR errors)
+    - Consistent pipeline (all documents normalized to PDF first)
 
 ### Pending
 - Q: What translation services to integrate with?