## 1. Core Implementation

- [x] 1.1 Update `RunE` in `client/cmd/root.go` to reject single-word bare arguments with an error message and non-zero exit
- [x] 1.2 Update usage template in `root.go` to reflect that note shorthand requires multiple words

## 2. Tests

- [x] 2.1 Add test: single bare word prints error to stderr and exits non-zero
- [x] 2.2 Add test: multiple bare words are submitted as a note (existing behavior preserved)
- [x] 2.3 Add test: zero arguments shows help (existing behavior preserved)