remove useless doc

docs/refactor_update_simulation.md

@@ -1,62 +0,0 @@
-# Refactoring Plan: Break Up update_simulation
-
-## Current State
-`update_simulation()` function is long with multiple responsibilities:
-1. Body RK4 updates and SOI transitions (~60 lines)
-2. Body global coordinate computation (~5 lines)
-3. Spacecraft RK4 updates (~15 lines)
-4. Maneuver execution checking (~20 lines)
-5. Spacecraft global coordinate computation (~15 lines)
-
-## Proposed Helper Functions
-
-### 1. `update_bodies_physics(SimulationState* sim)`
-- Handle body RK4 integration
-- Handle SOI transitions
-- ~60 lines of current body update logic
-
-### 2. `compute_body_globals(SimulationState* sim)`
-- Compute global coordinates for all bodies
-- Reuse existing function or inline it
-- ~5 lines
-
-### 3. `update_spacecraft_physics(SimulationState* sim)`
-- RK4 integration for spacecraft
-- ~15 lines
-
-### 4. `execute_pending_maneuvers(SimulationState* sim)`
-- Check maneuver triggers
-- Execute triggered maneuvers
-- ~20 lines
-
-### 5. `compute_spacecraft_globals(SimulationState* sim)`
-- Compute global coordinates for spacecraft
-- ~15 lines
-
-### 6. Simplified `update_simulation(SimulationState* sim)`
-```cpp
-void update_simulation(SimulationState* sim) {
-    update_bodies_physics(sim);
-    compute_body_globals(sim);
-    update_spacecraft_physics(sim);
-    execute_pending_maneuvers(sim);
-    compute_spacecraft_globals(sim);
-    sim->time += sim->dt;
-}
-```
-
-## Implementation Order
-1. Move body update logic to `update_bodies_physics()`
-2. Move spacecraft physics logic to `update_spacecraft_physics()`
-3. Create `execute_pending_maneuvers()` from existing maneuver loop
-4. Move spacecraft globals logic to `compute_spacecraft_globals()`
-5. Simplify `update_simulation()` to call helpers
-6. Update `simulation.h` with helper declarations
-7. Test to ensure behavior is identical
-
-## Benefits
-- Single responsibility for each function
-- Easier to test individual components
-- Cleaner `update_simulation()` that reads like a sequence
-- Easier to debug issues in specific areas
-- Functions can be reused or tested independently