Process leak: Update checker spawns infinite pnpm chain

Bug Report

Summary: Claude Code's update checker causes a catastrophic process leak where each pnpm view @anthropic-ai/claude-code@latest spawns another instance, creating a chain of thousands of processes.

Steps to Reproduce:

1. Run claude --dangerously-skip-permissions
2. Wait for update check to trigger
3. Observe exponential growth of pnpm processes

Evidence:

Parent: claude --dangerously-skip-permissions (PID 20495)
  └─ pnpm view @anthropic-ai/claude-code@latest (PID 55040)
      └─ pnpm view @anthropic-ai/claude-code@latest (PID 55050)
          └─ pnpm view @anthropic-ai/claude-code@latest (PID 55046)
              └─ ... infinite chain ...

Impact:

• Reached 5,000+ pnpm processes
• System memory exhaustion
• Requires manual kill of all pnpm processes

Expected: Single update check process that properly cleans up after completion

Environment:

• macOS Darwin 25.1.0
• pnpm (version via mise)

Workaround: Kill all pnpm processes: pkill -9 pnpm

Suggested Fix: Ensure update checker properly awaits spawned process and prevents recursive spawning.