Refactor `CreateSessionDialog` to be controlled by its parent instead
of using an internal `open` prop. Lift the state up to `JournalPanel`
and pass the creation callback through `JournalHeader` to
`SessionDropdown`.
Add a suite of dialogs and header components to manage journal
sessions, including:
- ConnectDialog for joining sessions with name and role selection
- CreateSessionDialog for starting new sessions
- InviteDialog for generating and copying player invite links
- SessionDropdown for switching between sessions (GM only)
- JournalHeader for displaying connection status and user info
hypercross