v1.5.1

v1.5.1: CreateNoteTweet support for Premium long posts via web fallback

Web session fallback now uses CreateNoteTweet GraphQL mutation for posts
>280 chars when account has Premium, fixing error 186 ("Tweet needs to be
a bit shorter") that occurred because CreateTweet hard-caps at 280 regardless
of Premium status.

Changes:
- xapi.rs: create_tweet_via_web() selects CreateNoteTweet vs CreateTweet based
  on text length + premium flag. Different query ID, richtext_options variable,
  and response path (data.notetweet_create vs data.create_tweet)
- config.rs: add graphql_create_note_tweet_id override for query ID rotation
- post.rs: preflight now shows critical issues (over_limit, empty_content) for
  replies too — previously all validation was skipped for replies
- Specific error message when Premium long post is rejected (suggests checking
  subscription status)