refactor: delete solitaire_data::solver wrapper; solve via card_game directly

Remove the standalone solver wrapper module. Its thin shaping — build a
solve-budgeted Session, run card_game::Session::solve(), extract the first
useful move — moves onto the domain type in solitaire_core as
GameState::solve_first_move() / GameState::solve_fresh_deal(), with the budget
consts and the SolveOutcome alias re-exported from solitaire_core.

Solving is deterministic, IO-free game logic, so core (which already owns
GameState and exposes session().solve()) is its correct home; solitaire_data is
the persistence/sync layer and never should have owned it.

Consumers now call the core API directly:
- engine: pending_hint (solve_first_move), game_plugin + play_by_seed_plugin
  (solve_fresh_deal), input_plugin (budget consts)
- assetgen: gen_seeds + gen_difficulty_seeds (solve_fresh_deal)

The solver tests move to solitaire_core. cargo test --workspace and
clippy --workspace --all-targets -- -D warnings both green.

Resolves the "delete the solver" directive — card_game provides the solver.

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

solitaire_engine/src/game_plugin.rs

@@ -15,9 +15,7 @@ use bevy::tasks::{AsyncComputeTaskPool, Task, futures_lite::future};
 use bevy::window::AppLifecycle;
 use solitaire_core::KlondikePile;
 use solitaire_core::{DrawMode, game_state::{GameMode, GameState}};
-use solitaire_data::solver::{
-    DEFAULT_SOLVE_MOVES_BUDGET, DEFAULT_SOLVE_STATES_BUDGET, try_solve,
-};
+use solitaire_core::{DEFAULT_SOLVE_MOVES_BUDGET, DEFAULT_SOLVE_STATES_BUDGET};
 #[allow(deprecated)]
 use solitaire_data::latest_replay_path;
 use solitaire_data::{
@@ -318,7 +316,7 @@ fn seed_from_system_time() -> u64 {
 }
 
 /// Walks forward from `initial_seed` (incrementing by 1 with wrapping
-/// arithmetic) until the [`solitaire_data::solver`] returns a verdict
+/// arithmetic) until the [`GameState::solve_fresh_deal`] returns a verdict
 /// the engine accepts as winnable, or until [`SOLVER_DEAL_RETRY_CAP`]
 /// attempts have elapsed.
 ///
@@ -393,7 +391,7 @@ fn poll_pending_new_game_seed(
 pub(crate) fn choose_winnable_seed(initial_seed: u64, draw_mode: DrawMode) -> u64 {
     let mut seed = initial_seed;
     for _ in 0..SOLVER_DEAL_RETRY_CAP {
-        match try_solve(
+        match GameState::solve_fresh_deal(
             seed,
             draw_mode,
             DEFAULT_SOLVE_MOVES_BUDGET,