Port conflict (EADDRINUSE) when running typegen and dev server simultaneously

# Port conflict (EADDRINUSE) when running typegen and dev server simultaneously

## Context

I'm using React Router DevTools with type generation tools (react-router typegen, safe-routes typegen).

## Reproduction

When running type generation tools and the development server simultaneously, both try to bind to port 42069 (used by TanStack DevTools), resulting in an `EADDRINUSE` error.

### Steps to Reproduce

```bash
# Terminal 1: Start dev server
pnpm dev

# Terminal 2: Run type generation
pnpm typegen
# or
react-router typegen
```

### Error Message

```
Error: listen EADDRINUSE: address already in use :::42069
```

## System Info

- **OS**: macOS 14.6.0 (Darwin 24.6.0)
- **Node**: v20.x
- **Package Manager**: pnpm 10.18.0
- **react-router-devtools**: 6.0.1
- **@tanstack/devtools**: 5.x
- **Vite**: 6.3.6

## Used Package Manager

pnpm

## Expected Behavior

Type generation tools and the dev server should be able to run simultaneously without port conflicts. The DevTools should automatically disable itself when running in a type generation context.

## Actual Behavior

The second process fails to start due to port 42069 already being in use by TanStack DevTools, which is initialized by both the dev server and type generation process.

## Possible Solution

Detect type generation context (via environment variables like `TYPEGEN_RUNNING=1` or command-line arguments) and disable DevTools initialization when running type generation, preventing unnecessary port binding.

Implementation approach:
- Check for typegen indicators: `TYPEGEN_RUNNING=1`, `SAFE_ROUTES_TYPEGEN=1`, `process.argv` includes "typegen"
- Return empty plugin array when in typegen context
- Maintain backward compatibility for normal dev mode

No source file or test is named. Start by tracing the DevTools initialization shared by the dev server and typegen entry points, then inspect the listed environment variables and process arguments. Done means both pnpm dev and the type generation commands run together without the EADDRINUSE error while normal DevTools behavior is preserved.

Written by the indexing model from the issue text.