fix+refactor+docs: P0–P3 todo list items

P0 fixes:
- Register WinSummaryPlugin, SelectionPlugin, CardAnimationPlugin in main.rs
  (all three were exported but never wired — features silently did nothing)
- game_state::draw(): increment move_count on waste→stock recycle, not just
  on normal draws; add move_count_increments_on_recycle regression test

P1 fixes:
- solitaire_server/Cargo.toml: remove duplicate dev-dependencies
  (solitaire_sync, uuid, chrono, jsonwebtoken were in both sections)

P2 — input_plugin refactor:
- Split 198-line handle_keyboard() into three focused systems under 110 lines each:
  handle_keyboard_core (U/N/Z/D/Space), handle_keyboard_hint (H), handle_keyboard_forfeit (G)
- Introduce KeyboardConfirmState resource to share countdown timers across systems
- Add three new unit tests: all_hints_suggests_draw_*, all_hints_is_empty_when_truly_stuck,
  new_game_confirm_window_is_positive

P2 — achievement predicate tests (solitaire_core):
- Add 10 direct unit tests for speed_demon, lightning, no_undo, high_scorer,
  on_a_roll, comeback predicates (previously only covered via check_achievements())
- 141 core tests now passing

P2 — server tests:
- solitaire_server/src/sync.rs: 4 unit tests for merge logic (no DB required)
- solitaire_server/src/leaderboard.rs: 2 unit tests for entry shape and sort order

P3 — documentation:
- Add struct-level ///  to 12 Plugin structs (ChallengePlugin, CursorPlugin,
  AnimationPlugin, HelpPlugin, PausePlugin, AudioPlugin, DailyChallengePlugin,
  HudPlugin, LeaderboardPlugin, OnboardingPlugin, TimeAttackPlugin, WeeklyGoalsPlugin)
- Add field-level /// to Card, Pile, Deck, GameState, AchievementContext, AchievementDef
- Add /// to WeeklyGoalKind, WeeklyGoalDef, WeeklyGoalContext, StatsExt::update_on_win

card_animation module (new files from previous session):
- chain.rs, diagnostics.rs, tuning.rs, updated interaction.rs/animation.rs/mod.rs/lib.rs
- Remove unused HOVER_SCALE_DEFAULT / DRAG_LIFT_SCALE_DEFAULT / HOVER_LERP_SPEED_DEFAULT constants
- Add handle_touch_stock_tap so touch users can draw from the stock pile

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

solitaire_engine/src/card_animation/mod.rs

@@ -73,17 +73,23 @@
 //! | `apply_drag_visual` scale + `CardAnimation` scale | ✓ (same filter) |
 
 pub mod animation;
+pub mod chain;
 pub mod curves;
+pub mod diagnostics;
 pub mod interaction;
 pub mod timing;
+pub mod tuning;
 
 pub use animation::{retarget_animation, win_scatter_targets, CardAnimation};
+pub use chain::AnimationChain;
 pub use curves::{sample_curve, MotionCurve};
+pub use diagnostics::{FrameTimeDiagnostics, WINDOW_SIZE as DIAG_WINDOW_SIZE};
 pub use interaction::{BufferedInput, HoverState, InputBuffer};
 pub use timing::{
     cascade_delay, compute_duration, micro_vary, DEAL_INTERVAL_SECS, MAX_DURATION_SECS,
     MIN_DURATION_SECS, WIN_CASCADE_INTERVAL_SECS,
 };
+pub use tuning::{AnimationTuning, InputPlatform};
 
 use bevy::prelude::*;
 
@@ -94,14 +100,18 @@ use crate::layout::LayoutResource;
 use crate::resources::DragState;
 
 use animation::advance_card_animations;
+use chain::advance_animation_chains;
+use diagnostics::update_frame_time_diagnostics;
 use interaction::{apply_drag_visual, apply_hover_scale, detect_hover, drain_input_buffer};
+use tuning::update_input_platform;
 
 // ---------------------------------------------------------------------------
 // Plugin
 // ---------------------------------------------------------------------------
 
 /// Registers all systems, resources, and components for curve-based card
-/// animation, hover visuals, drag lift, and input buffering.
+/// animation, hover visuals, drag lift, input buffering, platform-adaptive
+/// tuning, animation chaining, and frame-time diagnostics.
 ///
 /// Safe to register alongside `AnimationPlugin` and `FeedbackAnimPlugin` as
 /// long as no single entity carries both `CardAnim` and `CardAnimation`.
@@ -109,8 +119,8 @@ pub struct CardAnimationPlugin;
 
 impl Plugin for CardAnimationPlugin {
     fn build(&self, app: &mut App) {
-        // Register events and resources that interaction systems depend on,
-        // idempotently — double-registration is safe in Bevy.
+        // Register events and resources idempotently — double-registration is
+        // safe in Bevy.
         app.add_message::<MoveRequestEvent>()
             .add_message::<DrawRequestEvent>()
             .add_message::<UndoRequestEvent>()
@@ -118,12 +128,23 @@ impl Plugin for CardAnimationPlugin {
             .init_resource::<DragState>()
             .init_resource::<HoverState>()
             .init_resource::<InputBuffer>()
+            // Platform-adaptive tuning (desktop by default, switches on touch).
+            .init_resource::<AnimationTuning>()
+            // Rolling frame-time statistics.
+            .init_resource::<FrameTimeDiagnostics>()
             .add_systems(
                 Update,
                 (
-                    // Advance active animations (highest priority — runs first).
+                    // Detect input platform and update tuning — runs first so
+                    // all downstream systems in this frame see the fresh value.
+                    update_input_platform,
+                    // Frame-time diagnostics — cheap, runs unconditionally.
+                    update_frame_time_diagnostics,
+                    // Advance active animations.
                     advance_card_animations,
-                    // Interaction visuals (run after animation to read final positions).
+                    // After each animation finishes, pop the next chain segment.
+                    advance_animation_chains,
+                    // Interaction visuals (run after animation for final positions).
                     detect_hover,
                     apply_hover_scale,
                     apply_drag_visual,