docs: update LLM guides for completed architecture phase

Refresh the development guidance to point to layered src GUIDE files
and document Phase 4 completion, including AppShell extraction and
page driver/component adoption for non-maintenance pages.docs: update LLM guides for completed architecture phase

Refresh the development guidance to point to layered src GUIDE files
and document Phase 4 completion, including AppShell extraction and
page driver/component adoption for non-maintenance pages.

src/router/GUIDE.md

@@ -0,0 +1,31 @@
+# Router Guide
+
+`router` 集中管理 route、layout meta、auth meta 與 navigation guard。
+
+## routes.ts
+
+新增 route 時包含：
+
+- `path`
+- `name`
+- `component`
+- `meta.layout`
+
+一般頁面使用：
+
+```ts
+meta: { layout: 'default' }
+```
+
+只有登入頁、錯誤頁、維護中頁或明確要求獨立頁面時使用：
+
+```ts
+meta: { layout: 'none' }
+```
+
+## Guards
+
+- 登入需求使用既有 `requiresAuth` meta。
+- 訪客專用頁使用既有 `guestOnly` meta。
+- guard 流程放在 `guards.ts`，不要散落在 view/component。
+- catch-all route 保持在最後。