Let plop notes be written from the UI (#85 item 5)

journal_entries.planting_id was modelled, accepted by the API, and the
JournalPanel already rendered a "planting" badge for such entries — but
nothing in the UI ever created one. A badge for a state the UI couldn't
produce.

Give the plop the same "add note" affordance the bed inspector has:
- PlopInspector gains an onAddNote button ("📓 Add a note about this
  plant"), shown only to an editor (a viewer can't write notes).
- The editor store gains a journalPlantingId scope beside journalObjectId.
  The two are mutually exclusive — each setter clears the other — so the
  journal filter is never double-scoped.
- JournalPanel filters by plantingId when that scope is set, shows a
  "Notes about one planting · Show all" banner, and its composer attaches
  new notes to the plop. Empty-state copy updated to match.

Two taps from a selected plant to typing, mirroring the bed flow. No
backend change — the API already accepted plantingId.

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

web/src/pages/GardenEditorPage.tsx

@@ -85,6 +85,8 @@ export function GardenEditorPage() {
   const setRailTab = useEditorStore((s) => s.setRailTab)
   const journalObjectId = useEditorStore((s) => s.journalObjectId)
   const setJournalObjectId = useEditorStore((s) => s.setJournalObjectId)
+  const journalPlantingId = useEditorStore((s) => s.journalPlantingId)
+  const setJournalPlantingId = useEditorStore((s) => s.setJournalPlantingId)
   const journalCounts = useJournalCounts(gid)
   const capabilities = useCapabilities()
   const journalTotal = useMemo(
@@ -501,6 +503,13 @@ export function GardenEditorPage() {
             readOnly={!canEdit}
             onChangePlant={() => setPicker('change')}
             onClose={() => selectPlanting(null)}
+            onAddNote={() => {
+              // Parity with the bed inspector: scope the journal to this plop and
+              // open it. The plop stays selected, so the selection effect keeps the
+              // inspector reachable when you switch back.
+              setJournalPlantingId(selectedPlop.id)
+              setRailTab('journal')
+            }}
           />
         ) : (
           <p className="text-sm text-muted">Select a bed or a planting to edit it.</p>
@@ -521,6 +530,8 @@ export function GardenEditorPage() {
           objects={objects}
           scopeObjectId={journalObjectId}
           onScopeChange={setJournalObjectId}
+          scopePlantingId={journalPlantingId}
+          onScopePlantingChange={setJournalPlantingId}
         />
       ),
     },