Non-occluding mobile inspector + always-visible mode bar (#101)

Two things at once, because they're one layout: on a phone, selecting a bed
opened the rail as a bottom sheet that COVERED the whole garden, and opening
Journal/Assistant hid the mode bar until you closed it. You couldn't see what
you were editing, or switch modes without backing out.

Now the rail is an in-flow PEEK. Instead of `fixed bottom-0 max-h-70vh`
overlaying everything, EditorRail on mobile is a ≤50vh flex child the editor
places BETWEEN the canvas and the mode bar:

  canvas (flex-1, shrinks)  →  rail peek (≤50vh)  →  mode bar (always shown)

So the garden stays visible in the top band, the mode bar stays reachable
below, and you can tap another mode straight from an open panel. The
contextual tool strip yields to the peek (gated on !railTab), and tapping a
canvas mode closes the panel (deselecting if it was the inspector).

Desktop is untouched — the same EditorRail is the right-hand column there
(`md:` styles), the mode bar stays `md:hidden`.

Answers Steve's two calls from the end-of-run questions: always-visible mode
bar + non-occluding inspector. Verified live at 390px (inspector + journal
peeks keep the garden and mode bar visible; mode switching works) and 1280px
(desktop unchanged). tsc + vitest + build green; DESIGN updated.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01H3zbym8Doka2d7D48maSgZ

web/src/editor/EditorRail.tsx

@@ -47,9 +47,13 @@ export function EditorRail({
   return (
     <div
       className={cn(
-        // Phone: a bottom sheet over the canvas. Desktop: a column beside it.
-        'fixed inset-x-0 bottom-0 z-30 flex max-h-[70vh] flex-col rounded-t-xl border-t border-border bg-surface shadow-lg',
-        'md:static md:max-h-none md:w-80 md:shrink-0 md:rounded-xl md:border md:shadow-sm',
+        // Phone: an in-flow PEEK — a capped-height panel that sits between the
+        // canvas and the always-visible mode bar (the editor's flex column places
+        // it there), so the garden stays visible above it and the mode bar stays
+        // reachable below. The canvas flexes to fill whatever's left. Desktop: a
+        // fixed-width column beside the canvas.
+        'flex max-h-[50vh] min-h-0 shrink-0 flex-col rounded-t-xl border-t border-border bg-surface shadow-lg',
+        'md:static md:max-h-none md:w-80 md:rounded-xl md:border md:shadow-sm',
       )}
     >
       <div className="flex items-center gap-1 border-b border-border px-2 py-1.5">