feat: Add random thinking time for more natural cat responses

- Implement random delay between 300-1300ms instead of fixed 500ms
- Fix character encoding inconsistencies in tests (half-width tilde)
- Improve realistic interaction timing for cat responses

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: koki-develop

src/lib/cat.spec.ts

@@ -16,7 +16,7 @@ describe("Cat", () => {
 
   test("should respond with affection sounds for affection messages", async () => {
     const affectionMessages = ["可愛いね", "好きだよ", "撫でて"];
-    const affectionSounds = ["ﾆｬｵ～ﾝ", "ﾐｬｵ～", "ﾆｬﾝﾆｬﾝ"];
+    const affectionSounds = ["ﾆｬｵ~ﾝ", "ﾐｬｵ~", "ﾆｬﾝﾆｬﾝ"];
 
     for (const message of affectionMessages) {
       const response = await cat.response(message);
@@ -26,7 +26,7 @@ describe("Cat", () => {
 
   test("should respond with satisfaction sounds for satisfaction messages", async () => {
     const satisfactionMessages = ["ありがとう", "嬉しい", "素晴らしい"];
-    const satisfactionSounds = ["ｺﾞﾛｺﾞﾛ", "ﾆｬ～"];
+    const satisfactionSounds = ["ｺﾞﾛｺﾞﾛ", "ﾆｬ~"];
 
     for (const message of satisfactionMessages) {
       const response = await cat.response(message);
@@ -56,7 +56,7 @@ describe("Cat", () => {
 
   test("should respond with sleepy sounds for sleepy messages", async () => {
     const sleepyMessages = ["眠い", "疲れた", "おやすみ"];
-    const sleepySounds = ["ﾆｬ…", "ﾌﾆｬ～", "ﾆｬ～ﾝ"];
+    const sleepySounds = ["ﾆｬ…", "ﾌﾆｬ~", "ﾆｬ~ﾝ"];
 
     for (const message of sleepyMessages) {
       const response = await cat.response(message);

src/lib/cat.ts

@@ -88,8 +88,13 @@ export class Cat {
     return responses[index] as string;
   }
 
+  private getRandomThinkingTime(): number {
+    return Math.floor(Math.random() * 1000) + 300; // 300-1300ms
+  }
+
   async response(message: string): Promise<string> {
-    await new Promise((resolve) => setTimeout(resolve, 500));
+    const thinkingTime = this.getRandomThinkingTime();
+    await new Promise((resolve) => setTimeout(resolve, thinkingTime));
 
     const emotion = this.detectEmotion(message);
     return this.getRandomResponse(emotion);