fix(simulation): discard movement input while paused

process_player_input processed movement commands regardless of tick
rate, causing the camera to drift from the player when the game was
paused and the player held direction keys. Add PlayerAction::is_movement()
helper and a paused guard that skips movement actions while TickRate is
Paused. Pause/Unpause commands still process normally.

Fixes bug #3 (player moves while game is paused).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/simulation/input.rs

@@ -92,12 +92,17 @@ pub fn process_player_input(
     inventory_items: Query<(Entity, &CarriedBy, &ItemName, &InventorySlot)>,
 ) {
     let current_tick = time.tick;
+    let paused = time.paused();
     let inputs = input_queue.drain_for_tick(current_tick);
 
     // Track whether any movement was attempted this tick (for cooldown tick advance)
     let mut move_attempted = false;
 
     for input in inputs {
+        // Discard movement while paused (D-052). Pause/Unpause still processed.
+        if paused && input.action.is_movement() {
+            continue;
+        }
         match input.action {
             PlayerAction::MoveNorth => {
                 move_attempted = true;