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/editor/store.ts

@@ -59,6 +59,12 @@ interface EditorState {
   journalObjectId: number | null
   setJournalObjectId: (id: number | null) => void
 
+  // Which single plop the journal is filtered to, if any — the parallel of
+  // journalObjectId for a planting (#85). The two scopes are mutually exclusive
+  // (the setters clear each other), so the journal filter is never ambiguous.
+  journalPlantingId: number | null
+  setJournalPlantingId: (id: number | null) => void
+
   // The plant armed for placing plops (set after the PlantPicker choice); stays
   // armed for repeat-placement until cleared (Escape / done). null = not placing.
   armedPlant: Plant | null
@@ -116,7 +122,11 @@ export const useEditorStore = create<EditorState>((set) => ({
   setSeasonYear: (year) => set({ seasonYear: year }),
 
   journalObjectId: null,
-  setJournalObjectId: (id) => set({ journalObjectId: id }),
+  // Scoping to a bed clears any plop scope, so only one is ever active.
+  setJournalObjectId: (id) => set({ journalObjectId: id, journalPlantingId: null }),
+
+  journalPlantingId: null,
+  setJournalPlantingId: (id) => set({ journalPlantingId: id, journalObjectId: null }),
 
   armedPlant: null,
   armedLotId: null,
@@ -147,6 +157,7 @@ export const useEditorStore = create<EditorState>((set) => ({
       railTab: null,
       seasonYear: null,
       journalObjectId: null,
+      journalPlantingId: null,
       mode: DEFAULT_MODE,
     }),
 }))