Add Bluesky post helper with facet rendering and external link support

- Add BlueskyPostHelper for rendering Bluesky post facets (mentions, links, hashtags)
- Implement facet parsing and rendering with proper styling
- Add external link partial for non-Bluesky URLs
- Update DisplayedFile and PostFiles components to handle Bluesky posts
- Add comprehensive test coverage for helper methods
- Update scan user job to handle Bluesky-specific data

.cursorrules

@@ -12,6 +12,7 @@
 - If specs are failing, then fix the failures, and rerun with `bin/rspec <path_to_spec_file>`.
 - If you need to add logging to a Job to debug it, set `quiet: false` on the spec you are debugging.
 - Fish shell is used for development, not bash.
+- When running scratch commands, use `bin/rails runner`, not `bin/rails console`.
 
 # Typescript Development