Switch to cases/{new,in-progress,completed}/ directory structure

Replace single CASES_DIR with find_case_dir() that searches across
all status directories. New cases created in cases/new/{number}/.

Config: CASES_BASE, CASES_NEW, CASES_IN_PROGRESS, CASES_COMPLETED
Docker: added -v /home/chaim/legal-ai/cases:/cases volume mount

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

mcp-server/src/legal_mcp/tools/cases.py

@@ -60,7 +60,7 @@ async def case_create(
     )
 
     # Initialize git repo for the case
-    case_dir = config.CASES_DIR / case_number
+    case_dir = config.find_case_dir(case_number)
     case_dir.mkdir(parents=True, exist_ok=True)
     (case_dir / "documents").mkdir(exist_ok=True)
     (case_dir / "drafts").mkdir(exist_ok=True)
@@ -167,7 +167,7 @@ async def case_update(
     updated = await db.update_case(UUID(case["id"]), **fields)
 
     # Git commit the update
-    case_dir = config.CASES_DIR / case_number
+    case_dir = config.find_case_dir(case_number)
     if case_dir.exists():
         case_json = case_dir / "case.json"
         case_json.write_text(json.dumps(updated, default=str, ensure_ascii=False, indent=2))