music(player): 变速播放 + AB Loop

- 变速：底部 1× 圆形按钮循环切 0.5/0.75/1/1.25/1.5；preservesPitch=true（浏览器 native 保音高）；localStorage 持久化全局
- AB Loop：A B 两按钮在当前位置打点，🔁 开关；进度条上绿色高亮 A↔B 区段；timeupdate 触发 ≥B 跳回 A；切歌自动清 A/B

apps/werewolf/frontend/src/logic/assignment.ts

@@ -0,0 +1,102 @@
+// 角色分配 + role list 展开。RNG 注入，便于测试。
+
+export type RoleDict = Record<string, number>
+export type RoleList = string[]
+export type Preferences = Record<number, string[]> // player_id (1-based) -> 偏好角色列表
+
+export interface Rng {
+  // [0, 1)
+  next(): number
+}
+
+export const defaultRng: Rng = { next: () => Math.random() }
+
+/** 把 {狼人: 2, 村民: 1} 展开成 ['狼人', '狼人', '村民']。已是 list 则原样返回。 */
+export function expandRolesToList(roles: RoleDict | RoleList): RoleList {
+  if (Array.isArray(roles)) return [...roles]
+  const out: RoleList = []
+  for (const [role, count] of Object.entries(roles)) {
+    for (let i = 0; i < count; i++) out.push(role)
+  }
+  return out
+}
+
+/** 缩回 dict，方便存历史。 */
+export function rolesListToDict(roles: RoleList): RoleDict {
+  const out: RoleDict = {}
+  for (const r of roles) out[r] = (out[r] || 0) + 1
+  return out
+}
+
+// Fisher-Yates shuffle，用注入的 rng 保证可测。
+export function shuffle<T>(arr: T[], rng: Rng = defaultRng): T[] {
+  const a = [...arr]
+  for (let i = a.length - 1; i > 0; i--) {
+    const j = Math.floor(rng.next() * (i + 1))
+    ;[a[i], a[j]] = [a[j], a[i]]
+  }
+  return a
+}
+
+function weightedPick(weighted: string[], rng: Rng): string {
+  // weighted 是已经按权重展开的 list，直接随机选
+  const idx = Math.floor(rng.next() * weighted.length)
+  return weighted[idx]
+}
+
+/**
+ * 按偏好分配角色。
+ *
+ * 算法（从 partiverse python 同步）：
+ *  - 先随机化玩家顺序（保证公平 — 谁都可能先选）
+ *  - 维护剩余角色池
+ *  - 对每个玩家：偏好角色 4x 权重，其他 1x，加权随机抽一个
+ *  - 抽完从池里扣除
+ *
+ * 返回 list：index 0 = player 1 的角色。
+ */
+export function assignRolesWithPreferences(
+  rolesList: RoleList,
+  preferences: Preferences,
+  rng: Rng = defaultRng,
+): RoleList {
+  const numPlayers = rolesList.length
+  if (numPlayers === 0) return []
+
+  // 池：role -> 剩余 count
+  const pool: Record<string, number> = {}
+  for (const r of rolesList) pool[r] = (pool[r] || 0) + 1
+
+  const playerOrder = shuffle(
+    Array.from({ length: numPlayers }, (_, i) => i + 1),
+    rng,
+  )
+
+  const assignments: Record<number, string> = {}
+
+  for (const playerId of playerOrder) {
+    const preferred = new Set(preferences[playerId] || [])
+
+    const weighted: string[] = []
+    for (const [role, count] of Object.entries(pool)) {
+      if (count <= 0) continue
+      const w = preferred.has(role) ? count * 4 : count
+      for (let i = 0; i < w; i++) weighted.push(role)
+    }
+
+    if (weighted.length === 0) {
+      // 不该发生，兜底
+      assignments[playerId] = rolesList[playerId - 1]
+      continue
+    }
+
+    const picked = weightedPick(weighted, rng)
+    assignments[playerId] = picked
+    pool[picked] -= 1
+    if (pool[picked] === 0) delete pool[picked]
+  }
+
+  const out: RoleList = []
+  for (let i = 1; i <= numPlayers; i++) out.push(assignments[i])
+  return out
+}

apps/werewolf/frontend/src/logic/roles.ts

@@ -0,0 +1,46 @@
+// 全部 30 个角色，名字 = public/werewolf/roles/{name}.JPG 的 stem
+export const ALL_ROLES = [
+  '企鹅', '厚皮狼', '大公鸡', '女巫', '守卫', '守夜人', '小女孩', '小绵羊',
+  '憎恶猎人', '暴狼', '月夜祭司', '机械狼', '村民', '炸弹师', '熊', '爱神',
+  '狼人', '狼美人', '猎人', '白狼王', '白痴', '盗宝大师', '石像鬼', '禁锢之影',
+  '织梦人', '老酒鬼', '通灵师', '野孩子', '预言家', '骑士',
+] as const
+
+export type RoleName = (typeof ALL_ROLES)[number]
+
+// 默认预设。从 partiverse backend/activities/werewolf.py 同步。
+export const DEFAULT_PRESETS: Record<number, Record<string, number>> = {
+  8: { 狼人: 2, 守卫: 2, 女巫: 1, 猎人: 1, 骑士: 1, 白狼王: 1 },
+  9: { 狼人: 3, 守卫: 2, 女巫: 1, 猎人: 1, 骑士: 1, 白狼王: 1 },
+  10: { 狼人: 3, 守卫: 3, 女巫: 1, 猎人: 1, 骑士: 1, 白狼王: 1 },
+  12: { 狼人: 4, 守卫: 3, 女巫: 1, 猎人: 1, 骑士: 1, 白狼王: 1, 村民: 1 },
+}
+
+// preset 里出现过的角色排前面（频次降序，再按名字）
+function presetFrequency(): Record<string, number> {
+  const counts: Record<string, number> = {}
+  for (const preset of Object.values(DEFAULT_PRESETS)) {
+    for (const role of Object.keys(preset)) {
+      counts[role] = (counts[role] || 0) + 1
+    }
+  }
+  return counts
+}
+
+export function sortedRoles(): RoleName[] {
+  const counts = presetFrequency()
+  return [...ALL_ROLES].sort((a, b) => {
+    const da = counts[a] || 0
+    const db = counts[b] || 0
+    if (da !== db) return db - da
+    return a.localeCompare(b, 'zh-Hans-CN')
+  })
+}
+
+export function roleImageUrl(role: string): string {
+  return `/werewolf/roles/${encodeURIComponent(role)}.JPG`
+}
+
+export function backImageUrl(): string {
+  return '/werewolf/back.jpg'
+}