chore: complete @yume → @infiplot rename (post-PR#9)

PR #9 已完成首页和 layout 的视觉品牌迁移，此 commit 补齐剩余的
技术性改名 —— workspace 包名、source import、localStorage 键、
CSS keyframe、内部 header logo、.env.example、README。

- @yume/* → @infiplot/* (6 package.json + 17 imports + lockfile)
- localStorage/sessionStorage: yume:* → infiplot:*
  (含 PR #9 新增的 yume:hintClosed)
- CSS keyframe yume-ripple → infiplot-ripple
- new/play 页面 header logo "云梦" → "InfiPlot"
- 代码注释中的「云梦」style 形容词删除（layout.tsx, page.tsx）
- 根 package.json name + description（描述跟齐 staging
  "AI 实时交互剧情游戏"）
- README: tagline / Vercel deploy URL / 目录树 / engine 描述

保留：prompts.ts 的 LLM 体裁术语「视觉小说/galgame」、CustomForm
placeholder 的「视觉小说画风」（图像模型识别的风格名词）。

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/components/PlayCanvas.tsx

@@ -1,7 +1,7 @@
 "use client";
 
 import { useCallback, useEffect, useRef, useState } from "react";
-import type { Beat, BeatChoice } from "@yume/types";
+import type { Beat, BeatChoice } from "@infiplot/types";
 
 export type Phase =
   | "loading-first"        // first scene not yet rendered
@@ -439,7 +439,7 @@ export function PlayCanvas({
                   width: 30,
                   height: 30,
                   animation:
-                    "yume-ripple 1.6s cubic-bezier(0.16,1,0.3,1) infinite",
+                    "infiplot-ripple 1.6s cubic-bezier(0.16,1,0.3,1) infinite",
                 }}
               />
               <div