feat(engine): add daily challenge, level-up toast, and daily_devotee achievement

Phase 6 part 2 (partial):
- daily_seed_for(date) and PlayerProgress::record_daily_completion in
  solitaire_data, with streak logic that increments on consecutive days,
  resets on a skipped day, and is idempotent on same-day re-completions.
- DailyChallengePlugin tracks today's seed, awards +100 XP and updates
  the streak when the player wins a game whose seed matches. Pressing C
  starts a new game with the daily seed.
- LevelUpEvent toast in AnimationPlugin announces level changes.
- AchievementContext gains daily_challenge_streak; daily_devotee
  achievement unlocks at streak >= 7. AchievementPlugin reads
  ProgressResource and runs after ProgressUpdate.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

solitaire_data/src/lib.rs

@@ -48,6 +48,6 @@ pub use achievements::{
 
 pub mod progress;
 pub use progress::{
-    level_for_xp, load_progress_from, progress_file_path, save_progress_to, xp_for_win,
-    PlayerProgress,
+    daily_seed_for, level_for_xp, load_progress_from, progress_file_path, save_progress_to,
+    xp_for_win, PlayerProgress,
 };

solitaire_data/src/progress.rs

@@ -7,7 +7,7 @@ use std::fs;
 use std::io;
 use std::path::{Path, PathBuf};
 
-use chrono::{DateTime, NaiveDate, Utc};
+use chrono::{DateTime, Datelike, Duration, NaiveDate, Utc};
 use serde::{Deserialize, Serialize};
 
 const APP_DIR_NAME: &str = "solitaire_quest";
@@ -25,6 +25,15 @@ pub fn level_for_xp(xp: u64) -> u32 {
     }
 }
 
+/// Deterministic seed derived from a date, identical for all players globally.
+/// Used as the RNG seed for the daily-challenge deal.
+pub fn daily_seed_for(date: NaiveDate) -> u64 {
+    let y = date.year() as u64;
+    let m = date.month() as u64;
+    let d = date.day() as u64;
+    y * 10_000 + m * 100 + d
+}
+
 /// XP awarded for winning a game.
 ///
 /// Base 50 + scaled fast-win bonus (10..=50 for sub-2-minute wins) + 25 if
@@ -86,6 +95,29 @@ impl PlayerProgress {
     pub fn leveled_up_from(&self, prev_level: u32) -> bool {
         self.level > prev_level
     }
+
+    /// Record a daily-challenge completion for `date`.
+    ///
+    /// - First completion ever, or a gap of more than one day: streak resets to 1.
+    /// - Completion the day after the previous: streak increments.
+    /// - Same day as the previous: no-op (idempotent — a player can't double-count).
+    ///
+    /// Returns `true` if this call recorded a fresh completion (i.e. it wasn't
+    /// the same-day no-op case).
+    pub fn record_daily_completion(&mut self, date: NaiveDate) -> bool {
+        match self.daily_challenge_last_completed {
+            Some(last) if last == date => return false,
+            Some(last) if last + Duration::days(1) == date => {
+                self.daily_challenge_streak = self.daily_challenge_streak.saturating_add(1);
+            }
+            _ => {
+                self.daily_challenge_streak = 1;
+            }
+        }
+        self.daily_challenge_last_completed = Some(date);
+        self.last_modified = Utc::now();
+        true
+    }
 }
 
 /// Platform-specific default path for `progress.json`.
@@ -243,4 +275,61 @@ mod tests {
         save_progress_to(&path, &PlayerProgress::default()).expect("save");
         assert!(!path.with_extension("json.tmp").exists());
     }
+
+    // --- Daily challenge ---
+
+    #[test]
+    fn daily_seed_is_deterministic_per_date() {
+        let d = NaiveDate::from_ymd_opt(2026, 4, 24).unwrap();
+        assert_eq!(daily_seed_for(d), daily_seed_for(d));
+    }
+
+    #[test]
+    fn daily_seed_differs_across_dates() {
+        let a = NaiveDate::from_ymd_opt(2026, 4, 24).unwrap();
+        let b = NaiveDate::from_ymd_opt(2026, 4, 25).unwrap();
+        assert_ne!(daily_seed_for(a), daily_seed_for(b));
+    }
+
+    #[test]
+    fn first_daily_completion_starts_streak_at_1() {
+        let mut p = PlayerProgress::default();
+        let d = NaiveDate::from_ymd_opt(2026, 4, 24).unwrap();
+        let recorded = p.record_daily_completion(d);
+        assert!(recorded);
+        assert_eq!(p.daily_challenge_streak, 1);
+        assert_eq!(p.daily_challenge_last_completed, Some(d));
+    }
+
+    #[test]
+    fn consecutive_days_increment_streak() {
+        let mut p = PlayerProgress::default();
+        let d1 = NaiveDate::from_ymd_opt(2026, 4, 24).unwrap();
+        let d2 = d1 + Duration::days(1);
+        let d3 = d2 + Duration::days(1);
+        p.record_daily_completion(d1);
+        p.record_daily_completion(d2);
+        p.record_daily_completion(d3);
+        assert_eq!(p.daily_challenge_streak, 3);
+    }
+
+    #[test]
+    fn skipped_day_resets_streak_to_1() {
+        let mut p = PlayerProgress::default();
+        let d1 = NaiveDate::from_ymd_opt(2026, 4, 24).unwrap();
+        let d3 = d1 + Duration::days(2); // skipped d2
+        p.record_daily_completion(d1);
+        p.record_daily_completion(d3);
+        assert_eq!(p.daily_challenge_streak, 1);
+    }
+
+    #[test]
+    fn same_day_completion_is_idempotent() {
+        let mut p = PlayerProgress::default();
+        let d = NaiveDate::from_ymd_opt(2026, 4, 24).unwrap();
+        p.record_daily_completion(d);
+        let recorded_again = p.record_daily_completion(d);
+        assert!(!recorded_again, "same-day completion must report no-op");
+        assert_eq!(p.daily_challenge_streak, 1);
+    }
 }