Add real-time progress feedback to multi-run simulations

Switch from exec() to spawn() for streaming stderr, add onProgress
callback to runner, and emit per-run progress lines from workers.
CI now shows live percentage, tick count, and era during long runs.

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

packages/game-simulation/src/runner.ts

@@ -14,6 +14,7 @@ export interface SimulationConfig {
   seed?: number;
   verbose?: boolean;
   silent?: boolean;
+  onProgress?: (tick: number, totalTicks: number, era: string) => void;
 }
 
 export interface EraTransition {
@@ -139,8 +140,11 @@ export function runSimulation(config: SimulationConfig): SimulationResult {
       allMetrics.push(collectMetrics(state));
     }
 
-    if (!config.silent && tick % progressInterval === 0) {
-      printProgress(tick, config.totalTicks, state, startTime);
+    if (tick % progressInterval === 0) {
+      if (!config.silent) {
+        printProgress(tick, config.totalTicks, state, startTime);
+      }
+      config.onProgress?.(tick, config.totalTicks, state.meta.currentEra);
     }
   }