fix(game): restore exact media thresholds

Replace the inferred exponential media progression with the four initialized
32-bit thresholds used by the original score-addition path: 140,000, 650,000,
1,300,000, and 4,000,000. Award exactly one media level and extra ball at each,
with no nonexistent fifth tier.

Test Plan:
- `cargo test --all-targets` -- 50 passed
- `cargo clippy --all-targets -- -D warnings` -- passed
- `cargo build --profile production` -- passed
- threshold boundary and four-extra-ball test -- passed
- `git diff --cached --check` -- passed

tdkpin-rs/src/game.rs

@@ -586,10 +586,10 @@ impl Game {
     }
 
     fn check_media(&mut self, events: &mut Vec<Event>) {
-        const THRESHOLDS: [u32; 5] = [360_000, 720_000, 1_440_000, 2_880_000, 5_760_000];
+        const THRESHOLDS: [u32; 4] = [140_000, 650_000, 1_300_000, 4_000_000];
         let score = self.player().score;
         let level =
-            u8::try_from(THRESHOLDS.partition_point(|threshold| score >= *threshold)).unwrap_or(5);
+            u8::try_from(THRESHOLDS.partition_point(|threshold| score >= *threshold)).unwrap_or(4);
         if level > self.player().media_level {
             let player = &mut self.players[self.current_player];
             player.media_level = level;
@@ -1253,6 +1253,33 @@ mod tests {
         assert!(!game.effect_target_active());
     }
 
+    #[test]
+    fn media_extra_balls_use_the_recovered_threshold_table() {
+        let mut game = Game::new(1);
+        let mut events = Vec::new();
+
+        for (expected_level, threshold) in [140_000, 650_000, 1_300_000, 4_000_000]
+            .into_iter()
+            .enumerate()
+        {
+            game.players[0].score = threshold - 1;
+            game.check_media(&mut events);
+            assert_eq!(usize::from(game.player().media_level), expected_level);
+
+            game.players[0].score = threshold;
+            game.check_media(&mut events);
+            assert_eq!(usize::from(game.player().media_level), expected_level + 1);
+        }
+        assert_eq!(game.player().extra_balls, 4);
+        assert_eq!(
+            events
+                .iter()
+                .filter(|event| **event == Event::ExtraBall)
+                .count(),
+            4
+        );
+    }
+
     #[test]
     fn center_drain_advances_to_a_fresh_ball() {
         let mut game = Game::new(1);