fix: pass through terminal tab completion

[ZacharyZcR]

Refs Termix-SSH/Support#525

Summary

• keep app command autocomplete behavior when history suggestions match
• pass Tab through to the remote shell when command autocomplete is disabled, empty, or has no match
• avoids swallowing shell completion in the Electron terminal

Validation

• npx eslint src/ui/features/terminal/Terminal.tsx
• git diff --check
• npm run type-check