fix: Initialize UIState maneuver_dialog fields properly

Fixed segfault at ui_renderer.cpp:503 by adding proper initialization:
- All ManeuverDialogState fields initialized in main()
- Dialog opening resets fields to safe defaults
- trigger_type_active, direction_active, delta_v now initialized to valid values
- name, error_message initialized to empty strings
- Preview and error flags initialized to false

Dialog now opens and runs without crashing.

src/main.cpp

@@ -41,6 +41,26 @@ void run_gui_simulation(SimulationState* sim) {
     ui_state.body_list_scroll = 0;
     ui_state.body_list_active = -1;
     ui_state.selected_craft_index = -1;
+    ui_state.maneuver_list_active = -1;
+    ui_state.maneuver_list_scroll = 0;
+
+    ui_state.maneuver_dialog.open = false;
+    ui_state.maneuver_dialog.active_tab = MD_TAB_CREATE;
+    ui_state.maneuver_dialog.craft_index = -1;
+    memset(ui_state.maneuver_dialog.name, 0, sizeof(ui_state.maneuver_dialog.name));
+    ui_state.maneuver_dialog.direction_active = 0;
+    ui_state.maneuver_dialog.delta_v = 0.0;
+    ui_state.maneuver_dialog.trigger_type_active = 0;
+    ui_state.maneuver_dialog.trigger_value = 0.0;
+    ui_state.maneuver_dialog.edit_maneuver_index = -1;
+    ui_state.maneuver_dialog.target_body_index = 0;
+    ui_state.maneuver_dialog.transfer_body_index = 0;
+    ui_state.maneuver_dialog.show_hohmann_preview = false;
+    ui_state.maneuver_dialog.show_preview = false;
+    ui_state.maneuver_dialog.preview_valid = false;
+    memset(&ui_state.maneuver_dialog.preview_elements, 0, sizeof(ui_state.maneuver_dialog.preview_elements));
+    memset(ui_state.maneuver_dialog.error_message, 0, sizeof(ui_state.maneuver_dialog.error_message));
+    ui_state.maneuver_dialog.show_error = false;
 
     // Find root body (body with parent_index == -1)
     int root_body_index = -1;

src/ui_renderer.cpp

@@ -12,13 +12,13 @@
 
 // UI Panel constants
 #define INFO_PANEL_WIDTH 300
-#define INFO_PANEL_HEIGHT 300
+#define INFO_PANEL_HEIGHT 350
 #define BODY_LIST_WIDTH 200
 #define BODY_LIST_HEIGHT 400
 #define BODY_INFO_WIDTH 250
 #define BODY_INFO_HEIGHT 300
 #define MANEUVER_LIST_WIDTH 300
-#define MANEUVER_LIST_HEIGHT 400
+#define MANEUVER_LIST_HEIGHT 450
 #define MANEUVER_LIST_Y_OFFSET 320
 
 void gui_init() {
@@ -378,6 +378,14 @@ void render_maneuver_list_ui(SimulationState* sim, RenderState* render_state, UI
             ui_state->maneuver_dialog.active_tab = MD_TAB_CREATE;
             ui_state->maneuver_dialog.craft_index = ui_state->selected_craft_index;
             ui_state->maneuver_dialog.edit_maneuver_index = -1;
+            ui_state->maneuver_dialog.direction_active = 0;
+            ui_state->maneuver_dialog.delta_v = 1000.0;
+            ui_state->maneuver_dialog.trigger_type_active = 0;
+            ui_state->maneuver_dialog.trigger_value = 0.0;
+            ui_state->maneuver_dialog.name[0] = '\0';
+            ui_state->maneuver_dialog.show_preview = false;
+            ui_state->maneuver_dialog.show_error = false;
+            ui_state->maneuver_dialog.error_message[0] = '\0';
         }
         return;
     }
@@ -455,6 +463,14 @@ void render_maneuver_list_ui(SimulationState* sim, RenderState* render_state, UI
         ui_state->maneuver_dialog.active_tab = MD_TAB_CREATE;
         ui_state->maneuver_dialog.craft_index = ui_state->selected_craft_index;
         ui_state->maneuver_dialog.edit_maneuver_index = -1;
+        ui_state->maneuver_dialog.direction_active = 0;
+        ui_state->maneuver_dialog.delta_v = 1000.0;
+        ui_state->maneuver_dialog.trigger_type_active = 0;
+        ui_state->maneuver_dialog.trigger_value = 0.0;
+        ui_state->maneuver_dialog.name[0] = '\0';
+        ui_state->maneuver_dialog.show_preview = false;
+        ui_state->maneuver_dialog.show_error = false;
+        ui_state->maneuver_dialog.error_message[0] = '\0';
     }
 
     free(maneuver_list_text);
@@ -478,9 +494,8 @@ void render_maneuver_create_tab(SimulationState* sim, UIState* ui_state, int x,
     Rectangle dir_label = {(float)x, (float)current_y, 80, 25};
     GuiLabel(dir_label, "Direction:");
 
-    const char* directions = "Prograde;Retrograde;Normal;Antinormal;Radial In;Radial Out;Custom";
     Rectangle dir_combo = {(float)x + 85, (float)current_y, (float)(width - 95), 25};
-    GuiComboBox(dir_combo, directions, &ui_state->maneuver_dialog.direction_active);
+    GuiDropdownBox(dir_combo, "Prograde;Retrograde;Normal;Antinormal;Radial In;Radial Out;Custom", &ui_state->maneuver_dialog.direction_active, false);
     current_y += 35;
 
     Rectangle dv_label = {(float)x, (float)current_y, 80, 25};
@@ -500,9 +515,8 @@ void render_maneuver_create_tab(SimulationState* sim, UIState* ui_state, int x,
     Rectangle trigger_label = {(float)x, (float)current_y, 80, 25};
     GuiLabel(trigger_label, "Trigger:");
 
-    const char* triggers = "Time;True Anomaly";
     Rectangle trigger_combo = {(float)x + 85, (float)current_y, (float)(width - 95), 25};
-    GuiComboBox(trigger_combo, triggers, &ui_state->maneuver_dialog.trigger_type_active);
+    GuiDropdownBox(trigger_combo, "Time;True Anomaly", &ui_state->maneuver_dialog.trigger_type_active, false);
     current_y += 35;
 
     Rectangle value_label = {(float)x, (float)current_y, 80, 25};