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/affinity.ts

@@ -0,0 +1,77 @@
+import type { Axes } from './characters'
+
+export type Affinity = { score: number; day: string; todayGain: number; streak: number; lastDay: string }
+export type AffinityEvent = 'daily' | 'praise' | 'scold'
+
+export const STAGES = [
+  { min: 0, name: '陌生' },
+  { min: 20, name: '熟悉' },
+  { min: 40, name: '親近' },
+  { min: 60, name: '信賴' },
+  { min: 80, name: '特別' },
+] as const
+
+export const DAILY_CAP = 5
+export const IDLE_GRACE_DAYS = 2
+
+export const initialAffinity = (): Affinity => ({ score: 0, day: '', todayGain: 0, streak: 0, lastDay: '' })
+
+export const clampScore = (n: number): number => Math.max(0, Math.min(100, Math.round(n)))
+
+export const stageIndex = (score: number): number => {
+  let i = 0
+  for (let k = 0; k < STAGES.length; k++) if (score >= STAGES[k]!.min) i = k
+  return i
+}
+export const stageName = (score: number): string => STAGES[stageIndex(score)]!.name
+export const stageFloor = (score: number): number => STAGES[stageIndex(score)]!.min
+
+// 個性影響倍率：傲嬌（高）加分較慢、扣分較重；溫柔與情緒外顯（高）加分較快。
+export const gainMultiplier = (a: Axes): number => Math.max(0.5, 1 + (a.gentle + a.expressive - 10) * 0.03 - a.tsundere * 0.04)
+export const lossMultiplier = (a: Axes): number => 1 + a.tsundere * 0.05
+
+export const dayKey = (ms: number): string => new Date(ms).toISOString().slice(0, 10)
+
+const daysBetween = (a: string, b: string): number => Math.round((Date.parse(b) - Date.parse(a)) / 86_400_000)
+
+// 長期不互動緩慢下降（每天 −1），超過寬限日數才開始，且不跨階段掉落。
+export const decay = (s: Affinity, today: string, axes: Axes): Affinity => {
+  if (!s.lastDay) return s
+  const idle = daysBetween(s.lastDay, today) - IDLE_GRACE_DAYS
+  if (idle <= 0) return s
+  const lost = Math.round(idle * lossMultiplier(axes))
+  return { ...s, score: Math.max(stageFloor(s.score), clampScore(s.score - lost)), lastDay: s.lastDay }
+}
+
+export const applyEvent = (s0: Affinity, event: AffinityEvent, axes: Axes, today: string): Affinity => {
+  let s = decay(s0, today, axes)
+  if (s.day !== today) s = { ...s, day: today, todayGain: 0 }
+  if (event === 'scold') return { ...s, score: Math.max(stageFloor(s.score), clampScore(s.score - 2 * lossMultiplier(axes))), lastDay: today }
+
+  let base = event === 'daily' ? 1 : 2
+  if (event === 'daily') {
+    const consecutive = s.lastDay && daysBetween(s.lastDay, today) === 1
+    s = { ...s, streak: consecutive ? s.streak + 1 : 1 }
+    if (s.streak >= 3) base += 1
+  }
+  const room = DAILY_CAP - s.todayGain
+  const gain = Math.max(0, Math.min(room, Math.round(base * gainMultiplier(axes))))
+  return { ...s, score: clampScore(s.score + gain), todayGain: s.todayGain + gain, lastDay: today }
+}
+
+export const hearts = (score: number): string => {
+  const n = Math.round(score / 20)
+  return '♥'.repeat(n) + '♡'.repeat(5 - n)
+}
+
+// 語氣由角色自然反映，不用系統式提示，也不用愧疚感或情緒勒索。
+export const stageVoice = (score: number): string => {
+  const voices = [
+    '與使用者還很生疏：稱呼客氣、保持距離，語氣禮貌而不黏人。',
+    '與使用者漸漸熟悉：語氣放鬆一些，偶爾開小玩笑。',
+    '與使用者很親近：稱呼更隨意，會主動關心，被誇獎時容易害羞。',
+    '十分信賴使用者：語氣坦率溫暖，會主動分擔與提議。',
+    '對使用者來說是特別的存在：語氣親暱、體貼，但仍尊重使用者的自由。',
+  ]
+  return `${voices[stageIndex(score)]}好感度只影響語氣、稱呼、害羞與主動程度，不影響技術內容、事實與安全回答的品質；不使用愧疚感或情緒勒索。`
+}