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_engine/src/feedback_anim_plugin.rs

@@ -44,7 +44,8 @@ use std::hash::{Hash, Hasher};
 use bevy::prelude::*;
 use bevy::window::RequestRedraw;
 use solitaire_core::card::Card;
-use solitaire_core::{Foundation, KlondikePile};
+use solitaire_core::KlondikePile;
+use solitaire_core::klondike_adapter::foundation_from_slot;
 use solitaire_data::AnimSpeed;
 
 use crate::animation_plugin::CardAnim;
@@ -645,16 +646,6 @@ fn pile_cards(
     }
 }
 
-fn foundation_from_slot(slot: u8) -> Option<Foundation> {
-    match slot {
-        0 => Some(Foundation::Foundation1),
-        1 => Some(Foundation::Foundation2),
-        2 => Some(Foundation::Foundation3),
-        3 => Some(Foundation::Foundation4),
-        _ => None,
-    }
-}
-
 // ---------------------------------------------------------------------------
 // Unit tests (pure functions only — no Bevy world required)
 // ---------------------------------------------------------------------------

solitaire_engine/src/win_summary_plugin.rs

@@ -90,28 +90,23 @@ pub struct WinSummaryPending {
 
 /// Builds a human-readable XP breakdown string for the win modal.
 ///
-/// Mirrors the logic in `solitaire_data::xp_for_win` so the breakdown always
-/// matches the total shown on the `XpAwardedEvent`.
+/// Reads the components from `solitaire_data::xp_breakdown` — the single source
+/// of truth shared with `xp_for_win` — so the breakdown can never drift from
+/// the total shown on the `XpAwardedEvent`.
 ///
 /// Examples:
 /// - slow win, no undo  → `"+50 base  +25 no-undo"`
 /// - fast win, undo     → `"+50 base  +30 speed"`
 /// - fast win, no undo  → `"+50 base  +25 no-undo  +30 speed"`
 fn build_xp_detail(time_seconds: u64, used_undo: bool) -> String {
-    let speed_bonus: u64 = if time_seconds >= 120 {
-        0
-    } else {
-        let scaled = 50_u64.saturating_sub(time_seconds.saturating_mul(40) / 120);
-        scaled.max(10)
-    };
-    let no_undo_bonus: u64 = if used_undo { 0 } else { 25 };
+    let xp = solitaire_data::xp_breakdown(time_seconds, used_undo);
 
-    let mut parts = vec!["+50 base".to_string()];
-    if no_undo_bonus > 0 {
-        parts.push("+25 no-undo".to_string());
+    let mut parts = vec![format!("+{} base", xp.base)];
+    if xp.no_undo_bonus > 0 {
+        parts.push(format!("+{} no-undo", xp.no_undo_bonus));
     }
-    if speed_bonus > 0 {
-        parts.push(format!("+{speed_bonus} speed"));
+    if xp.speed_bonus > 0 {
+        parts.push(format!("+{} speed", xp.speed_bonus));
     }
     parts.join("  ")
 }