Address #121 review: keep sign-out reachable, dvh peek, exact height

- Fold the account menu into the editor's mobile strip. Hiding the global
  header removed the only sign-out on mobile in the editor; the strip now
  carries it, so the space win stays but sign-out is one tap away.
- EditorRail peek cap vh → dvh, matching the dvh-bounded editor column, so
  it can't overrun the visible viewport and push the mode bar off-screen.
- Mobile editor height 4rem → 3rem: with the header hidden, only <main>'s
  py-6 (3rem) is outside the editor, so 4rem left ~16px dead. Comment
  corrected.
- Trim two comments that duplicated nearby docs.

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

web/src/pages/GardenEditorPage.tsx

@@ -23,6 +23,7 @@ import { isCoarsePointer } from '@/editor/shared'
 import { cn } from '@/lib/cn'
 import type { EditorGarden } from '@/editor/types'
 import { ShareGardenModal } from '@/components/gardens/ShareGardenModal'
+import { AccountMenu } from '@/components/layout/AppShell'
 import { useMe } from '@/lib/auth'
 import {
   toEditorObject,
@@ -546,11 +547,11 @@ export function GardenEditorPage() {
   // the canvas bottom + Fit button under the browser chrome (#85).
   //
   // The subtracted band differs by breakpoint because the chrome does. On mobile
-  // the global top bar is hidden here (AppShell), so only <main>'s padding is
-  // above us — 4rem reclaims the ~48px the header used to cost the canvas. On
-  // desktop the header is present, so keep the original 8rem.
+  // the global top bar is hidden here (AppShell), so the only thing outside the
+  // editor is <main>'s py-6 — 3rem, top + bottom. On desktop the header is
+  // present, so keep the original 8rem.
   return (
-    <div className="flex h-[calc(100dvh-4rem)] flex-col gap-3 md:h-[calc(100dvh-8rem)] md:flex-row">
+    <div className="flex h-[calc(100dvh-3rem)] flex-col gap-3 md:h-[calc(100dvh-8rem)] md:flex-row">
       {/* Desktop-only control column. On mobile these move to the bottom mode bar
           + a slim top strip so the canvas — the point of the screen — isn't shoved
           into a corner by a stack of controls (#99). */}
@@ -627,6 +628,10 @@ export function GardenEditorPage() {
               Share
             </Button>
           )}
+          {/* The global header (and its account menu) is hidden on mobile in the
+              editor, so carry sign-out here — otherwise it's unreachable without
+              leaving the garden. */}
+          {me.data && <AccountMenu displayName={me.data.displayName} />}
         </div>
         {seasonYear !== null && <SeasonBanner year={seasonYear} onExit={() => setSeasonYear(null)} />}
         {/* Focus toolbar is desktop-only; on mobile its plant tools move to the
@@ -687,10 +692,8 @@ export function GardenEditorPage() {
           tabs={railTabs}
           activeId={railTab}
           onActivate={setRailTab}
-          // The inspector is read alongside the canvas, so it stays a half-height
-          // peek. Journal/History/Assistant are the task themselves — reading and
-          // typing want room — so they take a taller slice on mobile (the canvas
-          // above just needs to stay glanceable as the assistant edits it).
+          // Panel modes want the room; the inspector stays a shorter peek (see the
+          // `tall` prop doc).
           tall={railTab !== 'inspector'}
           onClose={() => {
             // Only the inspector is *about* the selection, so only closing it