i18n: translate all Chinese comments, docstrings, and logger messages to English

Comprehensive translation of Chinese text to English across the entire codebase:

- api/: FastAPI server documentation and logger messages
- cache/: Cache abstraction layer comments and docstrings
- database/: Database models and MongoDB store documentation
- media_platform/: All platform crawlers (Bilibili, Douyin, Kuaishou, Tieba, Weibo, Xiaohongshu, Zhihu)
- model/: Data model documentation
- proxy/: Proxy pool and provider documentation
- store/: Data storage layer comments
- tools/: Utility functions and browser automation
- test/: Test file documentation

Preserved: Chinese disclaimer header (lines 10-18) for legal compliance

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

media_platform/weibo/field.py

@@ -26,14 +26,14 @@ from enum import Enum
 
 
 class SearchType(Enum):
-    # 综合
+    # Comprehensive
     DEFAULT = "1"
 
-    # 实时
+    # Real-time
     REAL_TIME = "61"
 
-    # 热门
+    # Popular
     POPULAR = "60"
 
-    # 视频
+    # Video
     VIDEO = "64"