Flatten cases directory structure and unify paths

- Remove cases/new|in-progress|completed subdivision (status managed in DB)
- Rename documents/original → documents/originals (consistent plural)
- Move exports from global data/exports/ into cases/{num}/exports/
- Add documents/research/ for case law and analysis files
- Update all agents, scripts, config, web API endpoints, and DB paths

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

mcp-server/src/legal_mcp/services/docx_exporter.py

@@ -169,9 +169,9 @@ async def export_decision(case_id: UUID, output_path: str | None = None) -> str:
 
         _write_block_to_docx(doc, block_id, block["title"], content)
 
-    # Determine output path — versioned under data/exports/{case_number}/
+    # Determine output path — versioned under cases/{case_number}/exports/
     if not output_path:
-        export_dir = config.EXPORTS_DIR / case["case_number"]
+        export_dir = config.find_case_dir(case["case_number"]) / "exports"
         export_dir.mkdir(parents=True, exist_ok=True)
         # Find next version number
         existing = sorted(export_dir.glob("טיוטה-v*.docx"))