✨ 实现 Post.content 相关扩展协议 (#553)

* ✨ `post` 新增 `get_content()` 方法

* 🚨 make linter happy

* 💄 auto fix by pre-commit hooks

* 🐛 fix: 调整函数使用

* 💄 auto fix by pre-commit hooks

* ✨ 转用函数处理文本

* 💄 auto fix by pre-commit hooks

* 🔨 使用`Dict`存储`content_handlers`

* 💄 auto fix by pre-commit hooks

* 🎨 fix

* :arts: 简化函数使用

* 🐛 移除`Theme`的过时参数

* 🗑️ 复用 `self.plain_content`

* 💄 auto fix by pre-commit hooks

* ✨ 注册式装饰器写法

* 💄 auto fix by pre-commit hooks

* 🐛 fix

* 💄 auto fix by pre-commit hooks

* :feat: 通用纯文本处理函数

* 💄 auto fix by pre-commit hooks

* :downgrade: 复用`==`处理标题

* 🎨 简化（？）写法

* ✅ 测试修复

* ♻️ via ContentSupport extensions

* 🐛 fix test

* 💄 auto fix by pre-commit hooks

* 🐛 for clean text

* 🐛 fix

* 💄 auto fix by pre-commit hooks

* fix: for xml

* 💄 auto fix by pre-commit hooks

* chore: art

* 💄 auto fix by pre-commit hooks

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

nonebot_bison/theme/themes/basic/build.py

@@ -24,12 +24,15 @@ class BasicTheme(Theme):
 
         text += f"{post.title}\n\n" if post.title else ""
 
-        text += post.content if len(post.content) < 500 else f"{post.content[:500]}..."
+        content = await post.get_plain_content()
+        text += content if len(content) < 500 else f"{content[:500]}..."
 
         if rp := post.repost:
             text += f"\n--------------\n转发自 {rp.nickname or ''}:\n"
             text += f"{rp.title}\n\n" if rp.title else ""
-            text += rp.content if len(rp.content) < 500 else f"{rp.content[:500]}..."
+            rp_content = await rp.get_plain_content()
+
+            text += rp_content if len(rp_content) < 500 else f"{rp_content[:500]}..."
 
         text += "\n--------------\n"