Segmentation fault on /JPXDecode images in Termux (Android aarch64) - Proposed WITHOUT_JPX build option

### Description
On Termux (Android aarch64, Python 3.13), `docling-parse` crashes with a segmentation fault when encountering a PDF with JPEG 2000 (JPX) images. The crash occurs in the native C++ code during stream decoding.

### Environment
- **OS**: Android 11 (Termux)
- **Arch**: aarch64
- **Python**: 3.13
- **Library Version**: 1.0.0 (current source build)

### Root Cause
The crash happens in `src/parse/pdf_resources/page_xobject_image.h` within `init_stream_data()` when `qpdf_xobject.getStreamData()` is called on a stream filtered with `/JPXDecode`. This appears to be related to ABI conflicts or instability in the OpenJPEG backend when running in the Termux environment.

### Log Snippet
```log
2026-04-12 19:41:46.035 ( 0.053s) [ FC6C500] page_xobject_image.h:427 INFO| filter: /JPXDecode
2026-04-12 19:41:46.035 ( 0.053s) [ FC6C500] page_xobject_image.h:433 INFO| init_stream_data
2026-04-12 19:41:46.035 ( 0.053s) [ FC6C500] page_xobject_image.h:444 INFO| raw stream size: 21435 bytes
Fatal Python error: Segmentation fault
```

### Proposed Fix
Since JPX support is problematic on mobile/Android platforms and may not be required for all use cases, adding a `WITHOUT_JPX` build option allows the library to skip unstable decoding paths and maintain overall parser stability.

**1. CMakeLists.txt**
Add a toggle to make JPX support optional:
```cmake
option(WITHOUT_JPX OFF "Disable JPX support")
if(WITHOUT_JPX)
add_definitions(-DWITHOUT_JPX)
endif()
```

**2. src/parse/pdf_resources/page_xobject_image.h**
Implement a check and guard the decoding call:
```cpp
bool has_jpx_filter() const {
for(auto const& f : image_filters) {
if(f == "/JPXDecode") return true;
}
return false;
}

// In init_stream_data()
try {
bool skip_decoding = false;
#ifdef WITHOUT_JPX
if (has_jpx_filter()) skip_decoding = true;
#endif
if (!skip_decoding) {
decoded_stream_data = to_shared_ptr(qpdf_xobject.getStreamData());
} else {
LOG_S(WARNING) << "skipping decoding due to WITHOUT_JPX and /JPXDecode filter";
decoded_stream_data = nullptr;
}
} catch(...) { ... }
```

This fix has been verified locally on Termux and allows the rest of the document content (text, fonts, vectors) to parse successfully without crashing.