v1.11.0 "Podium"

Seventh release of the RustyNES-parity roadmap: RetroAchievements never loaded a game.

Fixed

• RetroAchievements never actually loaded a game. No code path ever called
  RaClient::begin_load_game — login worked, CheevosState::do_frame ran every
  emulated frame, and AchievementTriggered events were wired all the way to
  status-bar toasts, but with no game ever identified/loaded into rc_client,
  there was no achievement set to evaluate memory against, so achievements
  could never actually trigger. CheevosState::load_game/unload_game now
  wrap the missing calls, invoked from app.rs's MenuAction::OpenRom/
  CloseRom handlers (a no-op unless a user is logged in); a poll()-drained
  toast surfaces success/failure so the fix is observably verifiable, not just
  type-checked. This is the actual prerequisite bug blocking hardcore mode,
  leaderboards, and rich presence from meaning anything — found while scoping
  those features for this release.

Deferred (honestly scoped, not silently dropped)

• Splitting a new rustysnes-ra session/UI crate out of frontend/src/cheevos.rs's
  informal state, hardcore mode gating rewind/save-load/cheats/TAS, and
  leaderboard/rich-presence UI are all real, substantial features that were
  meaningless without the game-load fix above landing first. Pushed to a
  later, explicitly-scoped release. See to-dos/VERSION-PLAN.md's v1.11.0
  section.
• A ROM loaded via the CLI at startup, followed by a later login through the
  Tools window, is not retroactively announced to rc_client — the common
  path (launch, log in, then open a ROM via the File menu) is unaffected. See
  cheevos.rs's module doc.