Editor: the toolkit is a rail tab on desktop, and the rail is wider

The handoff drew the toolkit as a 216px card left of the plan. That width
was better spent on the plan and the rail, so the toolkit is now the rail's
first tab — Toolkit / Plot / Journal / History / Assistant — rendered
`embedded` (no card chrome, no heading; the tab is the heading), the grid
is two columns, and the rail grows from 336 to 400px.

Focusing a bed (double-click) switches the rail to Toolkit, because that is
where the plant palette now lives; a single click still selects into Plot.
The phone chrome is untouched: it never used the card.

Co-Authored-By: Claude Fable 5 <[email protected]>

web/src/editor/store.ts

@@ -17,7 +17,7 @@ export interface Viewport {
 export type Selection = { type: 'object'; id: number } | { type: 'plop'; id: number }
 
 /** The right-hand rail's tabs (desktop). */
-export type RailTab = 'plot' | 'journal' | 'history' | 'chat'
+export type RailTab = 'toolkit' | 'plot' | 'journal' | 'history' | 'chat'
 
 /** The phone's primary mode — which tools dock under the canvas. */
 export type PhoneMode = 'build' | 'plants' | 'journal' | 'chat'