Add height zones, jetpack boost particles, and TigerStyle guidelines

Level generator: add vertical variety with tall levels (46 tiles).
Segment generators accept ground_row parameter, SEG_CLIMB connects
height zones, transitions inherit predecessor ground row to prevent
walkability gaps. Climb segments respect traversal direction.

Jetpack boost: add blue flame particles during dash (burst + trail)
and continuous idle glow from player back while boost timer is active.

Camera: add 30px vertical look-ahead when player velocity exceeds
50 px/s.

Fix flame vent pedestal in gen_pit to use ground-relative position
instead of map bottom (broken in tall HIGH-zone levels).

Add TigerStyle coding guidelines to AGENTS.md adapted for C11.
Add tall_test.lvl (40x46) for height zone validation.

src/engine/particle.c

@@ -301,6 +301,137 @@ void particle_emit_jetpack_trail(Vec2 pos, Vec2 dash_dir) {
     particle_emit(&smoke);
 }
 
+void particle_emit_jetpack_boost_burst(Vec2 pos, Vec2 dash_dir) {
+    /* Blue flame accents mixed into the regular jetpack burst */
+    float exhaust_angle = atan2f(-dash_dir.y, -dash_dir.x);
+
+    /* Hot blue core — bright electric blue */
+    ParticleBurst core = {
+        .origin    = pos,
+        .count     = 10,
+        .speed_min = 90.0f,
+        .speed_max = 220.0f,
+        .life_min  = 0.15f,
+        .life_max  = 0.35f,
+        .size_min  = 2.0f,
+        .size_max  = 4.5f,
+        .spread    = 0.4f,
+        .direction = exhaust_angle,
+        .drag      = 2.5f,
+        .gravity_scale = 0.05f,
+        .color     = {80, 160, 255, 255},   /* electric blue */
+        .color_vary = true,
+    };
+    particle_emit(&core);
+
+    /* Outer blue-white flare */
+    ParticleBurst flare = {
+        .origin    = pos,
+        .count     = 8,
+        .speed_min = 40.0f,
+        .speed_max = 130.0f,
+        .life_min  = 0.2f,
+        .life_max  = 0.4f,
+        .size_min  = 1.5f,
+        .size_max  = 3.0f,
+        .spread    = 0.7f,
+        .direction = exhaust_angle,
+        .drag      = 3.0f,
+        .gravity_scale = 0.1f,
+        .color     = {140, 200, 255, 255},  /* light blue */
+        .color_vary = true,
+    };
+    particle_emit(&flare);
+}
+
+void particle_emit_jetpack_boost_trail(Vec2 pos, Vec2 dash_dir) {
+    /* Continuous blue flame trail while dashing with boost active */
+    float exhaust_angle = atan2f(-dash_dir.y, -dash_dir.x);
+
+    /* Blue flame sparks */
+    ParticleBurst sparks = {
+        .origin    = pos,
+        .count     = 2,
+        .speed_min = 50.0f,
+        .speed_max = 140.0f,
+        .life_min  = 0.1f,
+        .life_max  = 0.25f,
+        .size_min  = 1.5f,
+        .size_max  = 3.0f,
+        .spread    = 0.35f,
+        .direction = exhaust_angle,
+        .drag      = 3.0f,
+        .gravity_scale = 0.05f,
+        .color     = {60, 140, 255, 255},   /* bright blue */
+        .color_vary = true,
+    };
+    particle_emit(&sparks);
+
+    /* Blue-white wisps */
+    ParticleBurst wisps = {
+        .origin    = pos,
+        .count     = 1,
+        .speed_min = 20.0f,
+        .speed_max = 50.0f,
+        .life_min  = 0.15f,
+        .life_max  = 0.35f,
+        .size_min  = 2.0f,
+        .size_max  = 3.5f,
+        .spread    = 0.5f,
+        .direction = exhaust_angle,
+        .drag      = 3.5f,
+        .gravity_scale = -0.05f,
+        .color     = {160, 210, 255, 200},  /* pale blue */
+        .color_vary = true,
+    };
+    particle_emit(&wisps);
+}
+
+void particle_emit_jetpack_boost_idle(Vec2 pos, bool facing_left) {
+    /* Ambient blue flame simmering from the player's back while boost is
+     * active but the player isn't dashing. Exhaust drifts backward and
+     * slightly downward — a subtle idle glow effect. */
+    float exhaust_angle = facing_left ? 0.0f : (float)M_PI; /* away from facing */
+
+    /* Small blue sparks drifting backward */
+    ParticleBurst sparks = {
+        .origin    = pos,
+        .count     = 1,
+        .speed_min = 15.0f,
+        .speed_max = 45.0f,
+        .life_min  = 0.12f,
+        .life_max  = 0.3f,
+        .size_min  = 1.0f,
+        .size_max  = 2.5f,
+        .spread    = 0.8f,
+        .direction = exhaust_angle,
+        .drag      = 4.0f,
+        .gravity_scale = 0.15f,
+        .color     = {50, 130, 255, 220},   /* medium blue */
+        .color_vary = true,
+    };
+    particle_emit(&sparks);
+
+    /* Faint blue-white wisps floating up */
+    ParticleBurst wisps = {
+        .origin    = pos,
+        .count     = 1,
+        .speed_min = 8.0f,
+        .speed_max = 25.0f,
+        .life_min  = 0.15f,
+        .life_max  = 0.35f,
+        .size_min  = 1.5f,
+        .size_max  = 2.5f,
+        .spread    = 1.0f,
+        .direction = exhaust_angle - 0.3f,  /* slightly upward */
+        .drag      = 4.5f,
+        .gravity_scale = -0.1f,
+        .color     = {140, 200, 255, 160},  /* pale blue, translucent */
+        .color_vary = true,
+    };
+    particle_emit(&wisps);
+}
+
 void particle_emit_muzzle_flash(Vec2 pos, Vec2 shoot_dir) {
     float angle = atan2f(shoot_dir.y, shoot_dir.x);