refactor(core): move compute_time_bonus into scoring module

The win-time bonus is Ferrous house-rule scoring policy, not a bridge to
the upstream klondike crate, so it does not belong in klondike_adapter.
Relocate it to a dedicated solitaire_core::scoring module and update the
sole caller (win_summary_plugin) and the adapter/settings doc references.

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

solitaire_core/src/lib.rs

@@ -2,6 +2,7 @@ pub mod achievement;
 pub mod error;
 pub mod game_state;
 pub mod klondike_adapter;
+pub mod scoring;
 
 // Re-export the upstream types that cross the solitaire_core API boundary so
 // downstream crates (engine, wasm) can import from one place without a direct