chore: remove dead code and stale doc claims found in multi-agent sweep

Compiler-verified via RUSTFLAGS=--force-warn dead_code plus workspace-wide
reference greps; three parallel audit agents covered the engine crate, the
other eight crates, and Copilot commit-message-vs-diff drift.

Removed:
- replay_overlay/input.rs: 19 orphaned twins (~950 lines) of items also
  defined in mod.rs — the glob re-export made the mod.rs copies win and
  the file-level #![allow(dead_code)] hid the corpses. The live keyboard/
  button handlers and ReplayScrubKeyHold stay; the allow is retired.
- retarget_animation (never called; doc examples were its only refs)
- ScanThemesRequestEvent (never registered/written/read; its doc claimed
  a handle_scan_themes consumer that does not exist)
- _VEC3_REFERENCED workaround const + now-unneeded Vec3 import
- solitaire_data: load_stats/save_stats/time_attack_session_with_now
  default-path wrappers (the _from/_to variants are the live API) and
  surplus re-export names (settings MIN/MAX bounds, token loaders)
- solitaire_core: Session re-export (no external consumer)
- solitaire_wasm: ReplayPlayer::is_finished (no JS caller)
- solitaire_app: build_app wrapper (real entry is run())

Doc fixes:
- audio_plugin: WAV count 5→7, add FoundationCompletedEvent table row,
  drop bogus 'placeholder' label, bevy_kira_audio→kira
- ToastVariant::Warning: variant is live (5 writer plugins); dropped the
  stale allow(dead_code) and its 'currently unused' comment

Deliberately kept: Spider module (staged forward work), WinCascadePlugin
(documented alternative cascade, pending owner decision), SyncCompleteEvent
and solitaire_sync ApiError/merge_at (§8 change-controlled, flagged to owner).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

solitaire_data/src/lib.rs

@@ -105,10 +105,9 @@ pub use stats::{StatsExt, StatsSnapshot};
 pub mod storage;
 pub use storage::{
     TimeAttackSession, cleanup_orphaned_tmp_files, delete_game_state_at,
-    delete_time_attack_session_at, game_state_file_path, load_game_state_from, load_stats,
-    load_stats_from, load_time_attack_session_from, load_time_attack_session_from_at,
-    save_game_state_to, save_stats, save_stats_to, save_time_attack_session_to, stats_file_path,
-    time_attack_session_path, time_attack_session_with_now,
+    delete_time_attack_session_at, game_state_file_path, load_game_state_from, load_stats_from,
+    load_time_attack_session_from, save_game_state_to, save_stats_to, save_time_attack_session_to,
+    stats_file_path, time_attack_session_path,
 };
 
 pub mod achievements;
@@ -136,11 +135,9 @@ pub use difficulty_seeds::{DifficultySeeds, seeds_for};
 
 pub mod settings;
 pub use settings::{
-    AnimSpeed, REPLAY_MOVE_INTERVAL_MAX_SECS, REPLAY_MOVE_INTERVAL_MIN_SECS,
-    REPLAY_MOVE_INTERVAL_STEP_SECS, SOLVER_DEAL_RETRY_CAP, Settings, SyncBackend,
-    TIME_BONUS_MULTIPLIER_MAX, TIME_BONUS_MULTIPLIER_MIN, TIME_BONUS_MULTIPLIER_STEP,
-    TOOLTIP_DELAY_MAX_SECS, TOOLTIP_DELAY_MIN_SECS, TOOLTIP_DELAY_STEP_SECS, Theme, WindowGeometry,
-    load_settings_from, save_settings_to, settings_file_path,
+    AnimSpeed, REPLAY_MOVE_INTERVAL_STEP_SECS, SOLVER_DEAL_RETRY_CAP, Settings, SyncBackend,
+    TIME_BONUS_MULTIPLIER_STEP, TOOLTIP_DELAY_STEP_SECS, Theme, WindowGeometry, load_settings_from,
+    save_settings_to, settings_file_path,
 };
 
 #[cfg(target_os = "android")]
@@ -152,9 +149,7 @@ mod android_keystore;
 #[cfg(not(target_arch = "wasm32"))]
 pub mod auth_tokens;
 #[cfg(not(target_arch = "wasm32"))]
-pub use auth_tokens::{
-    TokenError, delete_tokens, load_access_token, load_refresh_token, store_tokens,
-};
+pub use auth_tokens::{TokenError, delete_tokens, store_tokens};
 
 pub mod sync_client;
 pub use sync_client::LocalOnlyProvider;