chore: code review cleanup + bump v0.8.4

- Remove _get_client_for_output() compat shim (replaced by direct _get_client calls)
- Remove unused inspect import
- Fix redundant branch in constants.get_accept_language()
- Add TWITTER_BROWSER docs to README (en + zh)
- Update all test monkeypatch signatures
- Bump version to 0.8.4

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "twitter-cli"
-version = "0.8.3"
+version = "0.8.4"
 description = "A CLI for Twitter/X — feed, bookmarks, and user timeline in terminal"
 readme = "README.md"
 license = "Apache-2.0"