feat(engine): UX iteration round — tooltip slider, streak fire, score breakdown

Three small UX improvements bundled because they share ui_theme token
edits.

Tooltip-delay slider in Settings → Gameplay
- Settings.tooltip_delay_secs (f32, #[serde(default)] = 0.5) tunable
  via "−" / "+" icon buttons next to a value readout. Range
  [TOOLTIP_DELAY_MIN_SECS, TOOLTIP_DELAY_MAX_SECS] = [0.0, 1.5] in
  TOOLTIP_DELAY_STEP_SECS (0.1) increments. "Instant" label when
  value is 0; "{n:.1} s" otherwise.
- ui_tooltip's hover-delay comparison reads from SettingsResource
  with MOTION_TOOLTIP_DELAY_SECS as the fallback when the resource
  is absent (test path). New tooltip_should_show(elapsed, delay)
  pure helper covers the boundary cases.
- adjust_tooltip_delay clamps; sanitized() carries the clamp through
  load. Five round-trip / default / legacy-deserialise tests.

Win-streak milestone fire animation
- New WinStreakMilestoneEvent { streak: u32 } fired from stats_plugin
  when win_streak_current crosses any of [3, 5, 10] (only the
  threshold crossing — not every subsequent win). HUD streak readout
  scale-pulses 1.0 → 1.20 → 1.0 over MOTION_STREAK_FLOURISH_SECS
  (0.6 s) on receipt; mirrors the foundation-flourish curve shape.
- Three threshold-crossing tests pin the firing contract.

Score-breakdown reveal on the win modal
- Win modal body replaces the single "Score: N" line with a
  per-component reveal: Base score, Time bonus (m:ss), No-undo
  bonus, Mode multiplier, separator, Total. Rows fade in over
  MOTION_SCORE_BREAKDOWN_FADE_SECS (0.12 s) staggered by
  MOTION_SCORE_BREAKDOWN_STAGGER_SECS (0.15 s) so the math reads as
  it animates. Skipped rows: zero time bonus, undo-tainted no-undo
  bonus, multiplier == 1.0.
- Honours AnimSpeed::Instant: rows spawn fully visible, no stagger.
- New ScoreBreakdown::compute helper sources base from
  GameWonEvent.score, time bonus from
  solitaire_core::scoring::compute_time_bonus, no-undo from a +25
  constant when undo_count == 0, mode multiplier from GameMode (Zen
  zeros the total). 9 new tests cover the math and the reveal
  cadence.

Test count net: +25 across the workspace (1007 → 1031).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

solitaire_engine/src/ui_tooltip.rs

@@ -34,6 +34,7 @@ use bevy::prelude::*;
 use bevy::ui::{ComputedNode, UiGlobalTransform};
 
 use crate::font_plugin::FontResource;
+use crate::settings_plugin::SettingsResource;
 use crate::ui_theme::{
     BG_ELEVATED_HI, BORDER_SUBTLE, MOTION_TOOLTIP_DELAY_SECS, RADIUS_SM, TEXT_PRIMARY,
     TYPE_CAPTION, VAL_SPACE_2, Z_TOOLTIP,
@@ -137,6 +138,23 @@ struct TooltipText;
 /// target's own border.
 const TOOLTIP_GAP_PX: f32 = 4.0;
 
+/// Pure helper: returns `true` once `elapsed_secs` has met or exceeded
+/// the player-configured `delay_secs`, so the tooltip should be revealed.
+///
+/// Treating "elapsed >= delay" as the show condition (rather than
+/// strictly greater than) is what makes a `delay_secs == 0.0` setting
+/// behave as advertised: on the very first tick after hover starts,
+/// `elapsed_secs` is `0.0` and the tooltip appears immediately. With a
+/// strict `>` the zero-delay case would still wait one tick.
+///
+/// Extracted so the comparison can be unit-tested without spinning up
+/// a Bevy `App` — `Time<Virtual>` clamps each tick to 250 ms under
+/// `MinimalPlugins`, which makes precise sub-second timing assertions
+/// awkward.
+pub(crate) fn tooltip_should_show(elapsed_secs: f32, delay_secs: f32) -> bool {
+    elapsed_secs >= delay_secs
+}
+
 // ---------------------------------------------------------------------------
 // Systems
 // ---------------------------------------------------------------------------
@@ -257,6 +275,7 @@ fn track_tooltip_hover(
 fn show_or_hide_tooltip(
     time: Res<Time>,
     state: Res<TooltipState>,
+    settings: Option<Res<SettingsResource>>,
     tooltips: Query<(&Tooltip, &UiGlobalTransform, &ComputedNode)>,
     tooltip_text_only: Query<&Tooltip>,
     mut overlay_q: Query<(&mut Node, &mut Visibility, &Children), With<TooltipOverlay>>,
@@ -280,9 +299,15 @@ fn show_or_hide_tooltip(
         return;
     };
 
+    // Player-configurable dwell delay; falls back to the design-token
+    // default when `SettingsResource` is absent (test harnesses running
+    // `UiTooltipPlugin` under `MinimalPlugins` without `SettingsPlugin`).
+    let delay_secs = settings
+        .as_ref()
+        .map(|s| s.0.tooltip_delay_secs)
+        .unwrap_or(MOTION_TOOLTIP_DELAY_SECS);
     let elapsed = time.elapsed().saturating_sub(started_at);
-    let delay = Duration::from_secs_f32(MOTION_TOOLTIP_DELAY_SECS);
-    if elapsed < delay {
+    if !tooltip_should_show(elapsed.as_secs_f32(), delay_secs) {
         hide(&mut visibility);
         return;
     }
@@ -550,4 +575,30 @@ mod tests {
             "overlay text must update to the new hovered entity's Tooltip string"
         );
     }
+
+    /// Test 5: `tooltip_should_show` is the pure helper that the system
+    /// uses to gate the reveal — exercising it directly avoids the
+    /// `Time<Virtual>` 250 ms clamp that makes precise sub-second
+    /// timing assertions in `MinimalPlugins` fiddly. The four cases
+    /// below cover the boundary semantics:
+    ///
+    /// * `delay = 0.0` ("Instant") must show on the first tick.
+    /// * `elapsed < delay` must NOT show.
+    /// * `elapsed == delay` must show (boundary inclusive).
+    /// * `elapsed > delay` must show.
+    #[test]
+    fn tooltip_should_show_respects_delay() {
+        // delay == 0 ("Instant"): any elapsed (including zero) shows.
+        assert!(tooltip_should_show(0.0, 0.0), "instant delay must show on first tick");
+        assert!(tooltip_should_show(0.5, 0.0));
+
+        // Standard non-zero delay.
+        assert!(!tooltip_should_show(0.4, 0.5), "elapsed < delay must hide");
+        assert!(tooltip_should_show(0.5, 0.5), "elapsed == delay must show (boundary)");
+        assert!(tooltip_should_show(0.6, 0.5), "elapsed > delay must show");
+
+        // Larger delay (max-end of the slider).
+        assert!(!tooltip_should_show(1.0, 1.5));
+        assert!(tooltip_should_show(1.5, 1.5));
+    }
 }