feat: 階段 2 路由、改寫與好感度

- Haiku 一次分類（難度、模型、思考程度、語氣），角色立刻回應
- turn.step 覆寫模型與思考程度，額度低於門檻自動降一級，支援手動鎖定
- 主模型回覆改寫為角色口吻，程式碼／路徑／指令／數字／URL 原樣保留，失敗回原文並另存原文 log
- 好感度規則、五階段、不跨階段掉落、個性倍率、狀態列愛心、/jsc-anima:anima-affinity
- 年齡與關係規則（未成年友情、成年移轉、戀愛式依賴需明確開啟）

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

hooks/router.ts

@@ -0,0 +1,58 @@
+export type ModelName = 'haiku' | 'sonnet' | 'opus'
+export type Effort = 'low' | 'medium' | 'high'
+export type Tone = 'neutral' | 'praise' | 'scold'
+export type Route = { difficulty: number; model: ModelName; effort: Effort; tone: Tone; ack: string }
+
+export const LADDER: readonly ModelName[] = ['haiku', 'sonnet', 'opus']
+
+export const FALLBACK_ROUTE: Route = { difficulty: 5, model: 'sonnet', effort: 'medium', tone: 'neutral', ack: '' }
+
+export const CLASSIFY_PROMPT =
+  '你是路由器。讀下面使用者輸入，只回傳一行 JSON：' +
+  '{"difficulty":1-10,"model":"haiku|sonnet|opus","effort":"low|medium|high","tone":"neutral|praise|scold","ack":"角色以口吻立刻回應的一句話"}。' +
+  'difficulty 低用 haiku，中用 sonnet，高或需深入推理用 opus；tone 是使用者對角色的態度（誇獎／感謝為 praise，責罵為 scold）。\n\n使用者輸入：\n'
+
+const isModel = (v: unknown): v is ModelName => v === 'haiku' || v === 'sonnet' || v === 'opus'
+const isEffort = (v: unknown): v is Effort => v === 'low' || v === 'medium' || v === 'high'
+const isTone = (v: unknown): v is Tone => v === 'neutral' || v === 'praise' || v === 'scold'
+
+export const parseRoute = (text: string): Route => {
+  const m = /\{[\s\S]*\}/.exec(text)
+  if (!m) return FALLBACK_ROUTE
+  try {
+    const j = JSON.parse(m[0]) as Record<string, unknown>
+    return {
+      difficulty: typeof j.difficulty === 'number' ? j.difficulty : FALLBACK_ROUTE.difficulty,
+      model: isModel(j.model) ? j.model : FALLBACK_ROUTE.model,
+      effort: isEffort(j.effort) ? j.effort : FALLBACK_ROUTE.effort,
+      tone: isTone(j.tone) ? j.tone : 'neutral',
+      ack: typeof j.ack === 'string' ? j.ack.slice(0, 200) : '',
+    }
+  } catch {
+    return FALLBACK_ROUTE
+  }
+}
+
+export type ChooseOptions = {
+  candidates: readonly ModelName[]
+  lockModel?: ModelName
+  lockEffort?: Effort
+  /** 最緊的額度剩餘百分比；低於 downgradeAt 就降一級。 */
+  quotaRemain?: number
+  downgradeAt: number
+}
+
+export const choose = (r: Route, o: ChooseOptions): { model: ModelName; effort: Effort; downgraded: boolean } => {
+  const effort = o.lockEffort ?? r.effort
+  if (o.lockModel) return { model: o.lockModel, effort, downgraded: false }
+  const allowed = LADDER.filter(m => o.candidates.includes(m))
+  const pool = allowed.length ? allowed : LADDER
+  let idx = Math.max(0, pool.indexOf(r.model))
+  if (!pool.includes(r.model)) idx = pool.length - 1 // 選到不在候選內的模型時取候選最強者
+  let downgraded = false
+  if (o.quotaRemain !== undefined && o.quotaRemain < o.downgradeAt && idx > 0) {
+    idx -= 1
+    downgraded = true
+  }
+  return { model: pool[idx]!, effort, downgraded }
+}