v1.0.9 — add Threads, Tumblr, and Bluesky to skill description

The CLI already supports connecting these platforms
(`accounts:connect threads`, `accounts:connect tumblr`,
`accounts:add-bluesky`), but the skill description had drifted and
only listed the original headline platform set. Add them so the
ClawHub listing and the agent's trigger text reflect actual support.

- SKILL.md: description + version 1.0.9
- package.json: version 1.0.9
- CHANGELOG: 1.0.9 entry
No CLI source changes.