rethinking boost

[huumn]

closes #1351
closes #194

This is done. It can be improved but it's good enough imo.

The intent here is to:

1. make job promotion use boost like normal items
2. make item "promotion" possible using boost
   • highest boost in territory gets pinned to top
   • when viewing "home" highest boost in all followed territories gets pinned at top
3. make adding boost not reliant on edits
   • if an item is our own, whether a comment or post, show the lightning bolt flipped horizontally which when pressed opens a modal to apply boost (this way they can work for comments too)

TODO

• allow jobs to be deleted
• expire boost after 30 days
• allow items to be boosted beyond edit window
• allow highest boosted item in territory to be pinned
• unify zap/downzap/boost button components/styling
• comment ranking for boost
• make sure boost is excluded from top

EXTRA TODO

• hint if boosted item is high enough to pin it or not
• review performance and see if there's something better that can be done
• squash all migrations for this into one