Scale round difficulty over time and add claimable powerups

Reshuffles the floor so the target color's share shrinks each round
(TargetDensityCalculator) instead of always averaging ~1/paletteSize,
making later rounds progressively harder to read.

Adds Super Speed and Air Blast powerups that spawn on the floor each
round, claimable by walking over or left-clicking their marker, expiring
after 2-3 unclaimed rounds. Usage is tracked in player stats.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

src/main/java/us/tss3/blockparty/config/ConfigManager.java

@@ -97,6 +97,71 @@ public class ConfigManager {
         return config.getBoolean("floor.shuffle-each-round", true);
     }
 
+    /** Fraction of the floor made of the target color on round 1 (0-1). Below the natural
+     *  1/paletteSize average so even the first round is harder than a plain uniform shuffle. */
+    public double getStartingTargetBlockFraction() {
+        return config.getDouble("floor.starting-target-fraction", 0.5);
+    }
+
+    /** Fraction of the floor made of the target color on the hardest (late-game) rounds. */
+    public double getMinimumTargetBlockFraction() {
+        return config.getDouble("floor.minimum-target-fraction", 0.06);
+    }
+
+    /** How much the target color's share of the floor shrinks per round after the first. */
+    public double getTargetBlockFractionReductionPerRound() {
+        return config.getDouble("floor.target-fraction-reduction-per-round", 0.04);
+    }
+
+    public boolean isPowerupsEnabled() {
+        return config.getBoolean("powerups.enabled", true);
+    }
+
+    /** Chance (0-1), rolled once per round, that a new powerup spawns on the floor. */
+    public double getPowerupSpawnChance() {
+        return config.getDouble("powerups.spawn-chance-per-round", 0.35);
+    }
+
+    /** Cap on how many unclaimed powerups can sit on the floor at once. */
+    public int getPowerupMaxActive() {
+        return config.getInt("powerups.max-active", 1);
+    }
+
+    /** Minimum number of rounds an unclaimed powerup lingers before disappearing. */
+    public int getPowerupMinLifetimeRounds() {
+        return config.getInt("powerups.min-lifetime-rounds", 2);
+    }
+
+    /** Maximum number of rounds an unclaimed powerup lingers before disappearing. */
+    public int getPowerupMaxLifetimeRounds() {
+        return config.getInt("powerups.max-lifetime-rounds", 3);
+    }
+
+    public org.bukkit.Material getPowerupMarkerMaterial(String typeKey) {
+        String name = config.getString("powerups.types." + typeKey + ".marker-block", "TORCH");
+        org.bukkit.Material material = org.bukkit.Material.matchMaterial(name);
+        return material != null ? material : org.bukkit.Material.TORCH;
+    }
+
+    public int getSuperSpeedDurationSeconds() {
+        return config.getInt("powerups.types.super-speed.duration-seconds", 8);
+    }
+
+    /** Potion effect amplifier, i.e. Speed (amplifier + 1) - amplifier 1 = Speed II. */
+    public int getSuperSpeedAmplifier() {
+        return config.getInt("powerups.types.super-speed.amplifier", 1);
+    }
+
+    /** Radius, in blocks, that Air Blast pushes other nearby players within. */
+    public double getAirBlastRadius() {
+        return config.getDouble("powerups.types.air-blast.radius", 4.0);
+    }
+
+    /** Horizontal+vertical knockback strength applied to players caught in an Air Blast. */
+    public double getAirBlastStrength() {
+        return config.getDouble("powerups.types.air-blast.strength", 1.4);
+    }
+
     public boolean isMusicEnabled() {
         return config.getBoolean("music.enabled", false);
     }