Fix terminal cleanup bounds checks

[BlackSquarre]

Summary

Fixes a crash when quitting NeoAsitop on layouts where the rendered tbox tree has fewer child items than fin(scr:) assumes.

The cleanup code previously indexed fixed positions such as:

• scr.items[0]
• scr.items[1]
• scr.items[0].items[2].items[0]
• loops over 0...2 / 0...1

On some machines/layouts, especially fanless configurations, those arrays can be shorter, causing:

Swift/ContiguousArrayBuffer.swift: Fatal error: Index out of range
Neoasitop.fin(scr:)

This change uses actual indices and guards nested fan cleanup before indexing.

Verification

Tested on:

• MacBookAir10,1
• Apple M1
• macOS 15.7.7

Commands/tests run:

DEVELOPER_DIR="/Applications/Xcode.app/Contents/Developer" \
xcodebuild -project socpowerbuddy_swift.xcodeproj \
  -scheme socpowerbuddy_swift \
  -configuration Release \
  MACOSX_DEPLOYMENT_TARGET=15.0 \
  build

Result:

** BUILD SUCCEEDED **

Also smoke-tested the TUI by launching NeoAsitop in a terminal-sized pty and pressing q.

Result:

Good Bye!

No Fatal error and no lingering process.