feat(FN-1757): clear residual lint debt in engine package

- Remove unused imports across 25 files in engine package
- Remove unused variable declarations in ipc-worker.ts, child-process-runtime.ts, and mission-autopilot.ts
- Clean up unnecessary imports in agent-instructions.ts, agent-tools.ts, cron-runner.ts, executor.ts, and other modules
- Minor cleanup in notifier.ts, peer-exchange-service.ts, pi.ts, plugin-runner.ts, and other files
- Improves code quality and reduces potential confusion from unused code

packages/engine/src/agent-instructions.ts

@@ -109,7 +109,7 @@ function formatPerformanceFeedbackSection(ratingSummary: AgentRatingSummary): st
   if (recentComments.length > 0) {
     lines.push("- Recent feedback:");
     for (const rating of recentComments) {
-      lines.push(`  - \"${rating.comment?.trim()}\" (score: ${rating.score.toFixed(1)})`);
+      lines.push(`  - "${rating.comment?.trim()}" (score: ${rating.score.toFixed(1)})`);
     }
   }