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>

README.md

@@ -1,6 +1,6 @@
 # 笔临 (Bilin)
 
-长篇创作智能协作平台 — Electron 桌面客户端 v0.1.0（P0/P1）
+长篇创作智能协作平台 — Electron 桌面客户端 v0.2.0（P2）
 
 ## 开发
 
@@ -14,13 +14,14 @@ npm run dev
 ## 测试
 
 ```bash
-npm run test      # 单元测试 6/6
-npm run test:e2e  # E2E 测试（需先 build）
 npm run build
+npm run test      # 单元测试
+npm run test:e2e  # E2E 测试（需先 build）
 ```
 
 ## 文档
 
-- 设计规格：`docs/superpowers/specs/2026-07-05-bilin-p0-p1-design.md`
-- 实现计划：`docs/superpowers/plans/2026-07-05-bilin-p0-p1.md`
+- P2 设计规格：`docs/superpowers/specs/2026-07-06-bilin-p2-design.md`
+- P2 实现计划：`docs/superpowers/plans/2026-07-06-bilin-p2.md`
+- P0/P1 设计规格：`docs/superpowers/specs/2026-07-05-bilin-p0-p1-design.md`
 - UI 原型：`design/ui_pc.html`