refactor: remove leftover redundancies after card_game migration

Post-migration audit found the card_game/klondike migration essentially
complete; these are the four small redundancies that remained:

- core: delete dead GameState::compute_time_bonus (zero callers; engine
  uses the klondike_adapter free fn directly)
- data: drop dead public re-exports load_latest_replay_from /
  save_latest_replay_to (no callers outside replay.rs); keep
  latest_replay_path (engine legacy migration still uses it)
- data+engine: lift win-XP scoring into a shared XpBreakdown so the
  win-summary modal breakdown and xp_for_win share one source of truth
  instead of duplicating the speed/no-undo constants
- engine: replace feedback_anim_plugin's private foundation_from_slot
  copy with the canonical klondike_adapter::foundation_from_slot

cargo test --workspace + clippy -D warnings green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

solitaire_core/src/game_state.rs

@@ -1,7 +1,6 @@
 use crate::error::MoveError;
 use crate::klondike_adapter::{
     DrawMode, KlondikeAdapter, SavedInstruction,
-    compute_time_bonus as scoring_time_bonus,
     foundation_from_slot as adapter_foundation_from_slot,
     skip_cards_from_count as adapter_skip_cards_from_count,
     tableau_from_index as adapter_tableau_from_index,
@@ -1118,11 +1117,6 @@ impl GameState {
             })
     }
 
-    /// Time bonus added to score on win: `700_000 / elapsed_seconds` (0 if elapsed is 0).
-    pub fn compute_time_bonus(&self) -> i32 {
-        scoring_time_bonus(self.elapsed_seconds)
-    }
-
     /// Read-only access to the underlying [`card_game::Session`] for this deal.
     ///
     /// Exposes `session.history()` (deterministic replay) and `session.solve()`