Address inspector-peek review: stale docs + selection cleanup

Gadfly on #101:
- EditorRail's module doc still described a "fixed 20rem column / bottom
  sheet"; updated to the in-flow peek (desktop column, phone ≤50vh peek
  between canvas and mode bar).
- (correctness) A canvas-mode tap only deselected when railTab was
  'inspector', so a selection made, then routed through Journal/Assistant,
  survived a return to Fixtures/Plants — the canvas kept highlighting it
  with no inspector. Canvas modes now clear the selection unconditionally.
- Dedup: the "closing the inspector deselects" pair lived in both selectMode
  and the rail's onClose; extracted a clearSelection() helper (also used by
  exitFocus) and fixed the now-stale "leave an inspector alone" comment.

tsc + vitest + build green.

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

web/src/pages/GardenEditorPage.tsx

@@ -225,17 +225,25 @@ export function GardenEditorPage() {
     }
   }, [selectedId, selectedPlantingId, setRailTab, setMode])
 
-  const exitFocus = () => {
-    setFocusedObject(null)
-    setArmedPlant(null)
+  // Clearing the selection also closes the inspector via the selection effect
+  // above; shared by exitFocus, the mode bar, and the rail's close so the
+  // deselect logic lives in one place.
+  const clearSelection = () => {
     select(null)
     selectPlanting(null)
   }
 
-  // The mobile mode bar. Journal/Assistant are panel modes, so they open the
-  // rail sheet; Fixtures/Plants are canvas modes, so they close a panel rail (but
-  // leave an inspector, which is about the selection, alone). Tapping Fixtures
-  // means going back to arranging objects, so it steps out of a focused bed.
+  const exitFocus = () => {
+    setFocusedObject(null)
+    setArmedPlant(null)
+    clearSelection()
+  }
+
+  // The mobile mode bar. Journal/Assistant are panel modes, so they open the rail
+  // as a peek; Fixtures/Plants are canvas modes — a fresh intent — so they close
+  // whatever's in the rail AND drop any lingering selection (which the canvas
+  // would otherwise keep highlighted, e.g. after routing a selection through
+  // Journal and back). Fixtures also steps out of a focused bed.
   const selectMode = (m: EditorMode) => {
     setMode(m)
     if (m === 'journal') {
@@ -244,12 +252,7 @@ export function GardenEditorPage() {
     } else if (m === 'assistant') {
       setRailTab('chat')
     } else {
-      // A canvas mode closes whatever's in the rail; the inspector is about the
-      // selection, so closing it deselects too.
-      if (railTab === 'inspector') {
-        select(null)
-        selectPlanting(null)
-      }
+      clearSelection()
       setRailTab(null)
       if (m === 'fixtures' && focusedObjectId != null) exitFocus()
     }
@@ -648,8 +651,7 @@ export function GardenEditorPage() {
             // deselects; dismissing a panel leaves the canvas as you had it. Any
             // panel rail (journal/history/chat) drops back to a canvas mode.
             if (railTab === 'inspector') {
-              select(null)
-              selectPlanting(null)
+              clearSelection()
             } else {
               // Back to a canvas mode — Plants if you're still inside a bed, else
               // Fixtures. (Hardcoding Fixtures here docked the object palette inside