* feat(skills): salvage xitter skill from PR #1065
Adapt the X/Twitter skill onto current main without vendoring an external CLI.
Use upstream x-cli installation instructions, add a social-media category,
and align credential/setup guidance with Hermes conventions.
* docs(skills): explain X credential requirements in xitter skill
Clarify why the official X flow needs five credentials and call out the setup/cost friction explicitly.
