Optimize CI workflows for faster execution

Performance improvements:
- Cache node_modules in addition to ~/.npm to skip dependency installation
- Add TypeScript incremental compilation caching with tsBuildInfoFile
- Parallelize lint and typecheck steps to run concurrently
- Add performance flags: --prefer-offline, --no-audit, --no-fund for npm ci
- Increase Node.js memory limit to 4GB and thread pool size
- Cache build output directory for faster rebuilds
- Upgrade TypeScript target to ES2020 for faster compilation
- Disable Next.js telemetry to reduce overhead

Expected reduction: 5+ minutes → 2-3 minutes

🤖 Generated with [Claude Code](https://claude.ai/code)

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

tsconfig.json

@@ -1,6 +1,6 @@
 {
   "compilerOptions": {
-    "target": "ES2017",
+    "target": "ES2020",
     "lib": ["dom", "dom.iterable", "esnext"],
     "allowJs": true,
     "skipLibCheck": true,
@@ -13,6 +13,7 @@
     "isolatedModules": true,
     "jsx": "preserve",
     "incremental": true,
+    "tsBuildInfoFile": ".next/types/tsbuildinfo",
     "plugins": [
       {
         "name": "next"