feat: deliver P2 v0.2.0 with unified editor, search, and snapshots

Implement schema v2 migration, outline/setting/inspiration CRUD, unified TipTap editing, reference panel with mentions, FTS global search, chapter version history, writing landmarks, word frequency analysis, light theme contrast fixes, and full unit/E2E test coverage.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/renderer/stores/useReferenceStore.ts

@@ -0,0 +1,30 @@
+import { create } from 'zustand'
+
+type ReferenceTab = 'setting' | 'outline' | 'inspiration'
+
+interface ReferenceState {
+  open: boolean
+  tab: ReferenceTab
+  query: string
+  pinnedIds: string[]
+  setOpen: (open: boolean) => void
+  setTab: (tab: ReferenceTab) => void
+  setQuery: (query: string) => void
+  togglePin: (id: string) => void
+}
+
+export const useReferenceStore = create<ReferenceState>((set, get) => ({
+  open: false,
+  tab: 'setting',
+  query: '',
+  pinnedIds: [],
+  setOpen: (open) => set({ open }),
+  setTab: (tab) => set({ tab }),
+  setQuery: (query) => set({ query }),
+  togglePin: (id) => {
+    const pinned = get().pinnedIds
+    set({
+      pinnedIds: pinned.includes(id) ? pinned.filter((x) => x !== id) : [...pinned, id]
+    })
+  }
+}))