fix(multi): resolve 16 bugs from comprehensive rules and code review

Core (solitaire_core):
- fix(core): auto-complete now requires waste empty to prevent deadlock
- fix(core): reject multi-card moves from waste pile (Klondike rule)
- fix(core): reject foundation-to-foundation moves (score farming exploit)
- fix(core): undo restores score from snapshot baseline, not live score
- feat(scoring): add +5 flip bonus when face-down tableau card is exposed
- feat(scoring): add recycle penalty (Draw-1: -100/pass, Draw-3: -20/pass)

Engine (solitaire_engine):
- fix(engine): remove TokioRuntimeResource::default() panic; degrade gracefully
- fix(engine): add ModalScrim guard to handle_new_game spawn site
- fix(engine): add ModalScrim guard to spawn_restore_prompt spawn site
- fix(engine): add ModalScrim guard to check_no_moves spawn site

Server / Web (solitaire_server):
- fix(web): correct draw_mode casing in replay submission (DrawOne/DrawThree)
- fix(web): correct mode casing in replay submission (Classic) for leaderboard
- fix(web): trim recorded_at to YYYY-MM-DD for NaiveDate deserialization
- fix(server): move /avatars route outside auth middleware (was always 401)

Data / Sync (solitaire_data, solitaire_sync):
- fix(data): namespace Android token file under APP_DIR_NAME with migration
- fix(data): Android token store now multi-user (HashMap); no silent overwrite
- fix(sync): draw_one_wins + draw_three_wins invariant preserved after merge

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_server/src/lib.rs

@@ -146,7 +146,6 @@ fn build_router_inner(state: AppState, rate_limit: bool) -> Router {
         .route("/api/account", delete(auth::delete_account))
         .route("/api/me", get(auth::get_me))
         .route("/api/me/avatar", put(auth::upload_avatar))
-        .nest_service("/avatars", ServeDir::new("avatars"))
         .layer(axum_middleware::from_fn_with_state(
             state.clone(),
             middleware::require_auth,
@@ -198,7 +197,8 @@ fn build_router_inner(state: AppState, rate_limit: bool) -> Router {
         .route("/api/daily-challenge", get(challenge::daily_challenge))
         .route("/api/replays/recent", get(replays::recent))
         .route("/api/replays/{id}", get(replays::get_by_id))
-        .route("/health", get(health));
+        .route("/health", get(health))
+        .nest_service("/avatars", ServeDir::new("avatars"));
 
     // Replay web UI: a single HTML page served at `/replays/:id` plus a
     // ServeDir for the static assets (`web/index.html`, `web/replay.css`,