refactor: dynamic UA matching, session reuse, score Optional, --output on all commands

- constants.py: sync_chrome_version() aligns UA/sec-ch-ua with impersonate target
- auth.py: reuse shared cffi session instead of creating duplicate
- filter.py: eliminate double weight building in score_tweet
- models.py: Tweet.score → Optional[float] for accurate display
- cli.py: add --output to search/likes/user-posts for consistency

twitter_cli/models.py

@@ -49,7 +49,7 @@ class Tweet:
     lang: str = ""
     retweeted_by: Optional[str] = None
     quoted_tweet: Optional[Tweet] = None
-    score: float = 0.0
+    score: Optional[float] = None
 
 
 @dataclass