feat: cookie file cache with TTL + user --json

- Cookie cache: save to ~/.cache/twitter-cli/cookies.json (24h TTL)
- On 401/403 auth failure: auto-invalidate cache, re-extract from browser
- Cache uses 0600 permissions for security
- Add --json option to twitter user command for scripting
- Priority: env vars → cache file → browser extraction

uv.lock

@@ -950,7 +950,7 @@ wheels = [
 
 [[package]]
 name = "twitter-cli"
-version = "0.4.4"
+version = "0.4.6"
 source = { editable = "." }
 dependencies = [
     { name = "beautifulsoup4" },