fix: QQOfficialPlatformAdapter 消息解析新增 appid 参数以确保能获取用户头像地址；移除多余的 At 组件，仅给群聊类型添加 At 组件 (#6741)

[FlanChanXwO]

Closes #6741

Modifications / 改动点

1. _parse_from_qqofficial 方法新增 appid 参数

• 方法签名新增 appid: str 参数
• 所有调用该方法的入口（群消息、频道消息、私聊消息）都传入 self.platform.appid

2. 修复 self_id 的赋值逻辑

• 之前：硬编码为 "unknown_selfid" 或 "qq_official"
• 现在：使用实际的 appid，正确标识机器人身份

3. 优化 At 组件的添加逻辑

• 之前：对所有消息类型都添加 At(qq="qq_official")，这是不正确的
• 现在：
  • 群聊消息：添加 At(qq=appid) 用于 @ 机器人自身
  • 私聊消息：不再添加 At 组件

涉及文件

• astrbot/core/platform/sources/qqofficial/qqofficial_platform_adapter.py

• astrbot/core/platform/sources/qqofficial_webhook/qo_webhook_adapter.py

• This is NOT a breaking change. / 这不是一个破坏性变更。

Screenshots or Test Results / 运行截图或测试结果

self_id使用appid后这使得一些需要获取头像的插件可以正常使用，可以使用https://q.qlogo.cn/qqapp/{self_id}/{user_id}/100以获取用户头像；以及避免了无效的 At 组件影响判断私聊和群聊的判断

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Checklist / 检查清单

• 😊 If there are new features added in the PR, I have discussed it with the authors through issues/emails, etc.
  / 如果 PR 中有新加入的功能，已经通过 Issue / 邮件等方式和作者讨论过。

• 👀 My changes have been well-tested, and "Verification Steps" and "Screenshots" have been provided above.
  / 我的更改经过了良好的测试，并已在上方提供了“验证步骤”和“运行截图”。

• 🤓 I have ensured that no new dependencies are introduced, OR if new dependencies are introduced, they have been added to the appropriate locations in requirements.txt and pyproject.toml.
  / 我确保没有引入新依赖库，或者引入了新依赖库的同时将其添加到 requirements.txt 和 pyproject.toml 文件相应位置。

• 😮 My changes do not introduce malicious code.
  / 我的更改没有引入恶意代码。

Summary by Sourcery

Update QQ Official platform message parsing to use the platform appid for self-identification and adjust mention handling for different message types.

New Features:

• Pass the platform appid into QQOfficialPlatformAdapter message parsing to support correct bot identity and avatar-related features.

Bug Fixes:

• Use the actual platform appid as self_id instead of hardcoded placeholder values in QQ Official messages.
• Stop adding unnecessary At components to non-group QQ Official messages to avoid misclassifying private and group chats.

Enhancements:

• Only add an At component for QQ Official group messages, targeting the bot appid to represent self-mentions.
• Tighten the pipeline stage process method return type annotation to a simpler AsyncGenerator form.
• Default test fixture file writing to the environment's default encoding instead of hardcoding UTF-8.
• Remove an unused utils package initializer file.

Tests:

• Adjust the local filesystem component test to rely on the default string encoding when writing the demo skill file.