Address CodeRabbit: fix list_forms README wording, use 'is None' for submit_form fallback

Author: oleksandr-nc

README.md

@@ -368,7 +368,7 @@ call; the body is streamed in chunks rather than loaded into memory.
 
 | Tool | Permission | Description |
 |------|-----------|-------------|
-| `list_forms` | read | List forms (filter by ownership: owned / shared / all) |
+| `list_forms` | read | List forms (filter by ownership: "owned" or "shared"; omit for both) |
 | `get_form` | read | Get a form with questions, options, shares |
 | `list_questions` | read | List questions on a form |
 | `get_question` | read | Get a single question |

src/nc_mcp_server/tools/forms.py

@@ -441,7 +441,7 @@ async def submit_form(form_id: int, answers: dict[str, Any], share_hash: str | N
             f"apps/forms/api/v3/forms/{form_id}/submissions",
             json_data=body,
         )
-        return json.dumps(data) if data else '{"status": "submitted"}'
+        return '{"status": "submitted"}' if data is None else json.dumps(data)
 
     @mcp.tool(annotations=ADDITIVE_IDEMPOTENT)
     @require_permission(PermissionLevel.WRITE)