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/resources.rs

@@ -12,28 +12,72 @@ pub struct GameStateResource(pub GameState);
 
 /// Tracks an in-progress drag operation.
 ///
-/// When `cards` is empty there is no active drag. When non-empty, the listed cards
-/// are being moved by the user and should be rendered at the cursor position.
-#[derive(Resource, Debug, Clone, Default)]
+/// When `cards` is empty there is no active drag. When non-empty, the listed
+/// cards are being moved by the user and should be rendered at the cursor or
+/// touch position.
+///
+/// # Drag threshold
+///
+/// A drag is *pending* when `!cards.is_empty() && !committed`. The drag does
+/// not become *committed* (cards do not visually move) until the pointer has
+/// moved at least `AnimationTuning::drag_threshold_px` pixels from `press_pos`.
+/// This prevents accidental drags on quick taps, especially on touch screens.
+#[derive(Resource, Debug, Clone)]
 pub struct DragState {
+    /// IDs of the cards being dragged (bottom-to-top stacking order).
     pub cards: Vec<u32>,
+    /// Pile the drag originated from.
     pub origin_pile: Option<PileType>,
+    /// World-space offset from the cursor/touch to the bottom card's centre.
     pub cursor_offset: Vec2,
+    /// Z coordinate used for the dragged cards.
     pub origin_z: f32,
+    /// Screen-space position (logical pixels) where the press/touch began.
+    ///
+    /// Used to measure whether the drag threshold has been crossed.
+    pub press_pos: Vec2,
+    /// Whether the drag threshold has been crossed and visual drag is active.
+    ///
+    /// Cards are only lifted and repositioned once `committed = true`.
+    pub committed: bool,
+    /// Touch ID driving this drag, or `None` for a mouse drag.
+    pub active_touch_id: Option<u64>,
+}
+
+impl Default for DragState {
+    fn default() -> Self {
+        Self {
+            cards: Vec::new(),
+            origin_pile: None,
+            cursor_offset: Vec2::ZERO,
+            origin_z: 0.0,
+            press_pos: Vec2::ZERO,
+            committed: false,
+            active_touch_id: None,
+        }
+    }
 }
 
 impl DragState {
-    /// Returns true when no drag is currently in progress.
+    /// Returns `true` when no drag (pending or committed) is in progress.
     pub fn is_idle(&self) -> bool {
         self.cards.is_empty()
     }
 
-    /// Clears the drag state.
+    /// Returns `true` when a drag has been committed (cards are visually lifted).
+    pub fn is_committed(&self) -> bool {
+        self.committed
+    }
+
+    /// Resets all drag state to the idle/default values.
     pub fn clear(&mut self) {
         self.cards.clear();
         self.origin_pile = None;
         self.cursor_offset = Vec2::ZERO;
         self.origin_z = 0.0;
+        self.press_pos = Vec2::ZERO;
+        self.committed = false;
+        self.active_touch_id = None;
     }
 }