Refine asteroids: faster, sparser, with horizontal drift

Increase base fall speed (120→200), acceleration (200→350), and respawn
delay (3→6s). Add random horizontal drift (±60 px/s) so asteroids fall
at angles. Widen initial stagger (0-3→0-8s). Reduce moon level from 24
asteroids to 8, spread evenly across the level.

src/game/hazards.c

@@ -632,14 +632,19 @@ static void asteroid_update(Entity *self, float dt, const Tilemap *map) {
             ad->falling = true;
             ad->trail_timer = 0;
             ad->fall_speed = ASTEROID_FALL_SPEED;
+            /* Randomize drift direction each fall */
+            ad->drift_x = ((float)(rand() % 201) - 100.0f) / 100.0f * ASTEROID_DRIFT_MAX;
         }
         return;
     }
 
     /* Accelerate while falling (gravity-like) */
-    ad->fall_speed += 200.0f * dt;
+    ad->fall_speed += ASTEROID_ACCEL * dt;
     self->body.pos.y += ad->fall_speed * dt;
 
+    /* Apply horizontal drift */
+    self->body.pos.x += ad->drift_x * dt;
+
     /* Tumble animation */
     animation_update(&self->anim, dt);
 
@@ -794,12 +799,13 @@ Entity *asteroid_spawn(EntityManager *em, Vec2 pos) {
     ad->spawn_pos = pos;
     ad->falling = true;
     ad->fall_speed = ASTEROID_FALL_SPEED;
+    ad->drift_x = ((float)(rand() % 201) - 100.0f) / 100.0f * ASTEROID_DRIFT_MAX;
     ad->trail_timer = 0;
     ad->respawn_timer = 0;
     /* Stagger start times based on spawn position to avoid all falling at once */
     ad->start_delay = (pos.x * 0.013f + pos.y * 0.007f);
     ad->start_delay = ad->start_delay - (float)(int)ad->start_delay;  /* frac part */
-    ad->start_delay *= 3.0f;  /* 0-3s stagger */
+    ad->start_delay *= 8.0f;  /* 0-8s stagger */
     e->data = ad;
 
     animation_set(&e->anim, &anim_asteroid);

src/game/hazards.h

@@ -95,13 +95,16 @@ Entity *force_field_spawn(EntityManager *em, Vec2 pos);
 
 #define ASTEROID_WIDTH     14
 #define ASTEROID_HEIGHT    14
-#define ASTEROID_FALL_SPEED 120.0f   /* base fall speed (px/s)       */
+#define ASTEROID_FALL_SPEED 200.0f   /* base fall speed (px/s)       */
+#define ASTEROID_ACCEL     350.0f    /* fall acceleration (px/s^2)   */
+#define ASTEROID_DRIFT_MAX 60.0f     /* max horizontal drift (px/s)  */
 #define ASTEROID_DAMAGE    1
-#define ASTEROID_RESPAWN   3.0f      /* seconds before respawning    */
+#define ASTEROID_RESPAWN   6.0f      /* seconds before respawning    */
 
 typedef struct AsteroidData {
     Vec2  spawn_pos;                 /* original position (for reset)*/
     float fall_speed;                /* current fall velocity        */
+    float drift_x;                   /* horizontal velocity (px/s)   */
     float respawn_timer;             /* countdown while inactive     */
     bool  falling;                   /* true = falling, false = wait */
     float trail_timer;               /* particle trail interval      */