* fix(mobile): keep chat drafts and the sidebar reachable on iPad
Chat composer drafts now live in a module-level store keyed by host,
workspace and tab, so leaving the session screen no longer drops them.
On iPadOS 26 windowed mode the window buttons covered the top-left
header controls; a native launch hook adds their height to the root
safe area. A hidden sidebar now shows a Show sidebar button in the
session header.
* fix(mobile): preserve draft edits across chat remounts
* test(mobile): type sidebar header fixture as a partial controller