`mujoco_studio` crashes on Windows + AMD: `wglMakeCurrent` failed (error 2000)

### Intro

Hi!

I use MuJoCo for a human body simulation project.

### My setup

- MuJoCo 3.12.0 official Windows binary
- Windows 11 (build 26200), x64
- GPU: AMD Radeon RX 6700 XT (no NVIDIA)
- Driver: 32.0.21013.1000, OpenGL 4.6 (25.6.1.250522)

### What's happening? What did you expect?

`mujoco_studio.exe` with the default Filament OpenGL backend crashes on startup:

```
FEngine (64 bits) created at 0000023FDC17B1A0 (threading is enabled)
FEngine resolved backend: OpenGL
[ATI Technologies Inc.], [AMD Radeon RX 6700 XT], [4.6.0 Compatibility Profile Context 25.6.1.250522], [4.60]
Feature level: 3
Active workarounds:
allow_read_only_ancillary_feedback_loop
Backend feature level: 3
FEngine feature level: 1
PanicLog
in makeCurrent:296
reason: wglMakeCurrent() failed. hdc = 00000000620110F2

Windows error code: 2000. (null)
Link error in "mipmapDepth":
- glError=0
- LogInfo="(null)"
Postcondition
in operator():407
reason: OpenGL program mipmapDepth failed to link or compile
```

I expected Studio to open. Error 2000 is `ERROR_INVALID_PIXEL_FORMAT`. The shader error looks secondary (no current GL context).

On the same machine:

- `mujoco_studio.exe --gfx=classic` works
- `simulate.exe` works
- `mujoco_studio.exe --gfx=vulkan` → `Selected backend not supported in this build.`

This is not the AMD `simulate` sidebar bug (#639). Studio never gets a valid context.

SDL creates the window with `SDL_WINDOW_OPENGL` and MSAA (`window.cc`). Filament then builds its context on a dummy window with a different pixel format and calls `wglMakeCurrent` on the SDL window DC. AMD rejects that mismatch.

### Steps for reproduction

1. Unzip MuJoCo 3.12.0 for Windows.
2. Run `bin\mujoco_studio.exe` (no flags).
3. Process aborts with the log above.

### Minimal model for reproduction

Not needed.

### Code required for reproduction

Not needed.

### Confirmations

- [x] I searched the [latest documentation](https://mujoco.readthedocs.io/en/latest/overview.html) thoroughly before posting.
- [x] I searched previous [Issues](https://github.com/google-deepmind/mujoco/issues) and [Discussions](https://github.com/google-deepmind/mujoco/discussions), I am certain this has not been raised before.

Start with window.cc and reproduce the default mujoco_studio.exe launch on the listed Windows AMD setup, comparing it with --gfx=classic. Trace the SDL window and Filament context setup described in the report; done means the default OpenGL backend starts successfully without the wglMakeCurrent error while the existing classic path remains working.

Written by the indexing model from the issue text.