feat: AI改写功能集成角色数据 + UI优化

- 新增story_characters表和seed_characters.sql种子数据(27个角色)
- AI改写/续写功能注入角色信息(性别/年龄/外貌/性格)
- 首页UI下移避让微信退出按钮
- 个人中心页面布局重构

client/js/scenes/ProfileScene.js

@@ -140,6 +140,7 @@ export default class ProfileScene extends BaseScene {
     this.renderUserCard(ctx);
     this.renderTabs(ctx);
     this.renderList(ctx);
+    this.renderLogoutButton(ctx);
   }
 
   renderBackground(ctx) {
@@ -160,12 +161,6 @@ export default class ProfileScene extends BaseScene {
     ctx.textAlign = 'center';
     ctx.font = 'bold 17px sans-serif';
     ctx.fillText('个人中心', this.screenWidth / 2, 35);
-
-    // 设置按钮
-    ctx.fillStyle = 'rgba(255,255,255,0.6)';
-    ctx.font = '18px sans-serif';
-    ctx.textAlign = 'right';
-    ctx.fillText('⚙', this.screenWidth - 20, 35);
   }
 
   renderUserCard(ctx) {
@@ -223,10 +218,24 @@ export default class ProfileScene extends BaseScene {
     ctx.textAlign = 'left';
     ctx.fillStyle = '#ffffff';
     ctx.font = 'bold 16px sans-serif';
-    ctx.fillText(user.nickname || '游客用户', avatarX + avatarSize + 15, avatarY + 22);
+    const nickname = user.nickname || '游客用户';
+    ctx.fillText(nickname, avatarX + avatarSize + 15, avatarY + 22);
+    
+    // 昵称旁边的编辑按钮
+    const nicknameWidth = ctx.measureText(nickname).width;
+    const editNicknameBtnX = avatarX + avatarSize + 15 + nicknameWidth + 8;
+    ctx.fillStyle = 'rgba(255,255,255,0.15)';
+    this.roundRect(ctx, editNicknameBtnX, avatarY + 8, 24, 20, 10);
+    ctx.fill();
+    ctx.fillStyle = 'rgba(255,255,255,0.6)';
+    ctx.font = '11px sans-serif';
+    ctx.textAlign = 'center';
+    ctx.fillText('✎', editNicknameBtnX + 12, avatarY + 22);
+    this.editNicknameRect = { x: editNicknameBtnX, y: avatarY + 8, width: 24, height: 20 };
 
     ctx.fillStyle = 'rgba(255,255,255,0.4)';
     ctx.font = '11px sans-serif';
+    ctx.textAlign = 'left';
     ctx.fillText(`ID: ${user.userId || '未登录'}`, avatarX + avatarSize + 15, avatarY + 42);
 
     // 创作者标签
@@ -367,6 +376,34 @@ export default class ProfileScene extends BaseScene {
     ctx.restore();
   }
 
+  // 渲染底部退出登录按钮
+  renderLogoutButton(ctx) {
+    const btnW = 120;
+    const btnH = 40;
+    const btnX = (this.screenWidth - btnW) / 2;
+    const btnY = this.screenHeight - 70;
+    
+    // 按钮背景
+    ctx.fillStyle = 'rgba(239, 68, 68, 0.15)';
+    this.roundRect(ctx, btnX, btnY, btnW, btnH, 20);
+    ctx.fill();
+    
+    // 按钮边框
+    ctx.strokeStyle = 'rgba(239, 68, 68, 0.4)';
+    ctx.lineWidth = 1;
+    this.roundRect(ctx, btnX, btnY, btnW, btnH, 20);
+    ctx.stroke();
+    
+    // 按钮文字
+    ctx.fillStyle = '#ef4444';
+    ctx.font = '14px sans-serif';
+    ctx.textAlign = 'center';
+    ctx.fillText('退出登录', this.screenWidth / 2, btnY + 26);
+    
+    // 保存按钮区域
+    this.logoutBtnRect = { x: btnX, y: btnY, width: btnW, height: btnH };
+  }
+
   // 渲染版本列表头部（返回按钮+故事标题）
   renderVersionListHeader(ctx, startY) {
     const headerY = startY - 5;
@@ -764,17 +801,29 @@ export default class ProfileScene extends BaseScene {
       return;
     }
 
-    // 设置按钮（右上角）
-    if (y < 50 && x > this.screenWidth - 50) {
-      this.showSettingsMenu();
-      return;
+    // 退出登录按钮
+    if (this.logoutBtnRect) {
+      const btn = this.logoutBtnRect;
+      if (x >= btn.x && x <= btn.x + btn.width && y >= btn.y && y <= btn.y + btn.height) {
+        this.confirmLogout();
+        return;
+      }
     }
 
-    // 头像点击
+    // 头像点击（修改头像）
     if (this.avatarRect) {
       const rect = this.avatarRect;
       if (x >= rect.x && x <= rect.x + rect.width && y >= rect.y && y <= rect.y + rect.height) {
-        this.showAvatarOptions();
+        this.chooseAndUploadAvatar();
+        return;
+      }
+    }
+
+    // 昵称编辑按钮点击
+    if (this.editNicknameRect) {
+      const rect = this.editNicknameRect;
+      if (x >= rect.x && x <= rect.x + rect.width && y >= rect.y && y <= rect.y + rect.height) {
+        this.showEditNicknameDialog();
         return;
       }
     }