Add exports panel: versioned drafts, download, upload revisions, mark final

Export DOCX now saves to data/exports/{case_number}/ with auto-versioning
(טיוטה-v1, v2...). The case view UI shows all drafts with download buttons,
allows uploading revised versions (עריכה-v1...), and marking a version as
final (copies to training corpus for style learning).

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

mcp-server/src/legal_mcp/config.py

@@ -53,6 +53,7 @@ ANTHROPIC_API_KEY = os.environ.get("ANTHROPIC_API_KEY", "")
 # Data directory
 DATA_DIR = Path(os.environ.get("DATA_DIR", str(Path.home() / "legal-ai" / "data")))
 TRAINING_DIR = DATA_DIR / "training"
+EXPORTS_DIR = DATA_DIR / "exports"
 
 # Cases directory — new structure: cases/{new,in-progress,completed}/{case_number}/
 CASES_BASE = Path(os.environ.get("CASES_BASE", str(Path.home() / "legal-ai" / "cases")))