Respect ignored users, simplify chip onboarding, and reduce room discovery load

[mpiorowski]

Summary

• Makes ignore settings apply consistently to mention notifications, unread counts, and desktop notifications so ignored users do not keep surfacing through secondary chat surfaces.
• Fixes room-membership commands around synthetic chat entries so /members, /invite, and /leave do not accidentally target a stale real room.
• Reduces database load from public room discovery by avoiding member/message join fanout, and updates chip onboarding so new users start with 1,000 chips instead of receiving a daily stipend.

What changed

• Mention notification creation, listing, and unread counting now exclude actors ignored by the recipient.
• Ignoring a user refreshes the Mentions feed and unread count immediately.
• /leave can leave synthetic entries such as Mentions, News, Browse Rooms, Showcase, and Work without acting on the last selected real room.
• Home/End now move cursors in chat, news, settings, icon picker, showcase, and work text inputs instead of acting as global scroll shortcuts.
• Public topic room discovery now aggregates member and message counts per room instead of joining all members and messages together.
• New chip rows now start at 1000; the busted-player floor remains 100.

Behavior notes

• DMs still bypass ignored-user message filtering; leaving the DM remains the dismissal path.
• Existing mention notifications from a now-ignored actor are hidden from list and unread queries rather than deleted.
• End no longer jumps chat or embedded room chat to the most recent message.

Feature flags

• None

Screenshots / Video

• UI-visible terminal behavior changed. Screenshots or a short terminal recording still need to be attached before review.

Testing

• Automated coverage:
  • Added tests for mention notifications skipping recipients who ignore the actor.
  • Added tests for hiding existing mention notifications after ignoring an actor.
  • Added tests for synthetic entry command targeting and composer-room precedence.
  • Added coverage for the room rail Discord invite layout and the new initial chip balance constant.
• Manual verification:
  • Not included in the diff context.