refactor: clean test dump output with TestOutput struct

Replace manual buffer management (malloc/free/snprintf) with a simple
stack-allocated TestOutput helper. Uses dump_simulation_state's 4-param
API with a single dump_state() method. Verification stays as individual
INFO() calls outside the loop.

tests/test_rendezvous.cpp

@@ -27,6 +27,18 @@ static int find_spacecraft_by_name(SimulationState* sim, const char* name) {
     return -1;
 }
 
+// ── Test-only output helper ──────────────────────────────────────────────────
+
+struct TestOutput {
+    char buf[32768];
+    int offset = 0;
+
+    void dump_state(SimulationState* sim, const char* label) {
+        int n = dump_simulation_state(sim, label, buf + offset, sizeof(buf) - offset);
+        if (n > 0) offset += n;
+    }
+};
+
 
 TEST_CASE("Config loading for Hohmann transfer", "[rendezvous_hohmann][config]") {
     const double TIME_STEP = 30.0;
@@ -502,55 +514,38 @@ SCENARIO("Hohmann transfer rendezvous with validation", "[rendezvous_hohmann][in
         int arr_idx = add_maneuver_to_simulation(sim, &arrival);
         REQUIRE(arr_idx >= 0);
 
-        // Dump initial state
-        dump_simulation_state(sim, "INITIAL STATE");
+        // Compute expected step count from analytical times
+        const double expected_duration = wait_time + hohmann.transfer_time;
+        const int expected_steps = static_cast<int>(expected_duration / sim->dt);
+        // Safety limit: 1 year — prevents infinite loops if calculation is wrong
+        const double SAFETY_LIMIT_SECONDS = 3600.0 * 24.0 * 365.0;
 
-        // Run simulation
-        double sim_time = 0.0;
-        const double DT = 1.0;
-        const int MAX_STEPS = 700000;
+        TestOutput out;
         bool transfer_complete = false;
 
-        for (int i = 0; i < MAX_STEPS; i++) {
+        for (int i = 0; i < expected_steps + 1000; i++) {
             update_simulation(sim);
-            sim_time += DT;
 
-            // Dump state at key milestones
-            if (i == 0) {
-                dump_simulation_state(sim, "T=0 (initial)");
-            }
-            if (i == int(wait_time / DT)) {
-                dump_simulation_state(sim, "JUST BEFORE DEPARTURE");
-            }
-            if (i == int(wait_time / DT) + 1) {
-                dump_simulation_state(sim, "AFTER DEPARTURE BURN");
-            }
-            if (i == int(arrival_time / DT)) {
-                dump_simulation_state(sim, "JUST BEFORE ARRIVAL");
+            if (sim->time > SAFETY_LIMIT_SECONDS) {
+                INFO("\n=== SAFETY LIMIT REACHED ===");
+                INFO("sim->time: " << sim->time << " s (limit: " << SAFETY_LIMIT_SECONDS << " s)");
+                break;
             }
+
+            if (i == 0) out.dump_state(sim, "T=0 (initial)");
+            if (i == static_cast<int>(wait_time / sim->dt)) out.dump_state(sim, "JUST BEFORE DEPARTURE");
+            if (i == static_cast<int>(wait_time / sim->dt) + 1) out.dump_state(sim, "AFTER DEPARTURE BURN");
+            if (i == static_cast<int>(arrival_time / sim->dt)) out.dump_state(sim, "JUST BEFORE ARRIVAL");
             if (sim->maneuvers[arr_idx].executed && !transfer_complete) {
-                dump_simulation_state(sim, "AFTER ARRIVAL BURN");
+                out.dump_state(sim, "AFTER ARRIVAL BURN");
                 transfer_complete = true;
                 break;
             }
         }
 
-        INFO("\n=== FINAL STATE ===");
-        INFO("Final time: " << sim_time << " s");
-        INFO("Departure executed: " << sim->maneuvers[dep_idx].executed);
-        INFO("Arrival executed: " << sim->maneuvers[arr_idx].executed);
-        dump_simulation_state(sim, "FINAL STATE");
-
-        // Verify maneuvers executed
-        REQUIRE(sim->maneuvers[dep_idx].executed);
-        REQUIRE(sim->maneuvers[arr_idx].executed);
-
         // Verify rendezvous quality
         double final_radius = vec3_magnitude(chaser->local_position);
         double radius_error = fabs(final_radius - r2);
-        INFO("\nVerification:");
-        INFO("  Radius error: " << radius_error << " m");
-        INFO("  Chaser eccentricity: " << chaser->orbit.eccentricity);
 
         Vec3 chaser_vel = chaser->local_velocity;
         Vec3 target_vel = target->local_velocity;
@@ -560,10 +555,22 @@ SCENARIO("Hohmann transfer rendezvous with validation", "[rendezvous_hohmann][in
         double separation_distance = vec3_magnitude(separation);
         double relative_velocity = vec3_magnitude(vec3_sub(chaser_vel, target_vel));
 
+        INFO("\n=== FINAL STATE ===");
+        INFO("Final time: " << sim->time << " s");
+        INFO("Departure executed: " << sim->maneuvers[dep_idx].executed);
+        INFO("Arrival executed: " << sim->maneuvers[arr_idx].executed);
+        INFO("\nVerification:");
+        INFO("  Radius error: " << radius_error << " m");
+        INFO("  Chaser eccentricity: " << chaser->orbit.eccentricity);
         INFO("  Chaser speed: " << chaser_speed << " m/s");
         INFO("  Target speed: " << target_speed << " m/s");
         INFO("  Separation: " << separation_distance << " m");
         INFO("  Relative velocity: " << relative_velocity << " m/s");
+        INFO(out.buf);
+
+        // Verify maneuvers executed
+        REQUIRE(sim->maneuvers[dep_idx].executed);
+        REQUIRE(sim->maneuvers[arr_idx].executed);
 
         REQUIRE_THAT(radius_error, WithinAbs(10.0, 10.0));
         REQUIRE_THAT(chaser->orbit.eccentricity, WithinAbs(0.0, 0.001));