chore: ruff 代码检查与修复

130 issues auto-fixed (import ordering, UP045/UP006 type annotations),
33 issues manually fixed (E712/E501/E402/E722 + N818 rename + per-file
wechat ignore for N8xx naming conventions). All 33 tests pass.

app/crawler/base.py

@@ -2,7 +2,6 @@ import hashlib
 from abc import ABC, abstractmethod
 from dataclasses import dataclass, field
 from datetime import datetime
-from typing import List, Optional
 
 
 @dataclass
@@ -12,7 +11,7 @@ class CrawlResult:
     total_count: int = 0
     new_count: int = 0
     announcements: list = field(default_factory=list)
-    error_message: Optional[str] = None
+    error_message: str | None = None
     crawled_at: datetime = field(default_factory=datetime.now)
     duration: float = 0.0
 
@@ -24,7 +23,7 @@ class CrawlResult:
 @dataclass
 class PipelineConfig:
     filter_enabled: bool = True
-    keywords: List[str] = field(default_factory=list)
+    keywords: list[str] = field(default_factory=list)
     dedup_enabled: bool = True
     notify_mode: str = "filtered"
     mark_sent: bool = False