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/lib/outline-utils.ts

@@ -0,0 +1,36 @@
+import type { OutlineItem } from '@shared/types'
+
+export function buildOutlineTree(items: OutlineItem[]): OutlineItem[] {
+  const byParent = new Map<string | null, OutlineItem[]>()
+  for (const item of items) {
+    const key = item.parentId
+    if (!byParent.has(key)) byParent.set(key, [])
+    byParent.get(key)!.push({ ...item, children: [] })
+  }
+  const attach = (parentId: string | null): OutlineItem[] => {
+    const nodes = byParent.get(parentId) ?? []
+    nodes.sort((a, b) => a.sortOrder - b.sortOrder)
+    for (const node of nodes) {
+      node.children = attach(node.id)
+    }
+    return nodes
+  }
+  return attach(null)
+}
+
+export function flattenOutlineTree(items: OutlineItem[]): OutlineItem[] {
+  const result: OutlineItem[] = []
+  const walk = (nodes: OutlineItem[]): void => {
+    for (const node of nodes) {
+      result.push(node)
+      if (node.children?.length) walk(node.children)
+    }
+  }
+  walk(items)
+  return result
+}
+
+export function calcDeviation(expected: number | null, actual: number): number | null {
+  if (!expected || expected <= 0) return null
+  return Math.round(((actual - expected) / expected) * 100)
+}