feat: W8 強度 0～3、稱呼與安全規則 (#9)

以 prompt.compose hook 注入依強度與稱呼組成的規則段落；規則為純函式並附測試。

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

plugins/anime-companion/hooks/register.tsx

@@ -1,4 +1,15 @@
 import type { Register } from 'claude-code'
 
-// 骨架：載入後尚無 hook。人格卡注入與強度見 W7、W8（議題 #8、#9）。
-export const register: Register = () => {}
+import { resolveConfig } from './config'
+import { buildRules, SECTION_ID } from './rules'
+
+// 依強度與稱呼把規則段落加到系統提示最後；人格卡與檢索見 W5～W7。
+export const register: Register = (on, options) => {
+  const config = resolveConfig(options)
+  on('prompt.compose', async ($, e, next) => {
+    const result = await next(e)
+    const text = buildRules(config)
+    if (text === null) return result
+    return { sections: [...result.sections, { id: SECTION_ID, text, scope: 'session' }] }
+  })
+}