Contradictory definitions of the `just dev` command in README.md

There is a contradiction in the `README.md` file regarding what the `just dev` command actually does.

1. In the "Quick start" section (around line 171), it says that `just dev` starts both the relay and the desktop app:
`just dev # starts the relay + desktop app together`

2. Right below it (around line 176), in the instructions for a split-terminal workflow, it says to use `just desktop-dev` for the desktop app:
`For a split-terminal workflow (relay logs separate from Vite output), use just relay in one terminal and just desktop-dev in another.`

3. However, later in the "Common dev commands" section (around line 262), `just dev` is listed as running *only* the desktop app, which contradicts point 1:
`just dev # Run the desktop app`

Read README.md around the Quick start section near lines 171-176 and the Common dev commands section near line 262. Compare the documented behavior of just dev, relay, and desktop-dev, then revise the conflicting descriptions so the command behavior is consistent throughout. Done means both sections describe the same workflow accurately.

Written by the indexing model from the issue text.