Add support for embedded lens corrections in RawNIND/AI-denoised DNGs

[trougnouf]

Implement serialization of DNG OpcodeList2 and OpcodeList3 to preserve embedded lens correction data (warp rectilinear, vignette radial, gain maps) when writing DNG files.

Key changes:

• Add dt_dng_opcode_serialize_opcode_list_2() and _3() functions to serialize correction data from dt_image_t to DNG opcode list format
• Add _write_dng_opcode_lists() helper in imageio_dng.c to write opcode lists to TIFF directories using libtiff's TIFFTAG_OPCODELIST2/3 tags
• Modify dt_imageio_dng_write_cfa_bayer() and dt_imageio_dng_write_linear() to call _write_dng_opcode_lists() and preserve correction data
• Add fallback definitions for TIFFTAG_OPCODELIST* tags for older libtiff

This ensures that when RawNIND/AI-denoise creates a DNG file from a source image that has embedded lens corrections (e.g., from a DNG with OpcodeList3), those corrections are preserved in the output DNG and will be automatically applied when the denoised DNG is re-imported into darktable.

Fixes #21504

Generated by Mistral Vibe.

This was entirely vibe coded. I tested it on a Sony A7C ARW picture on Arch Linux and it worked well; there is a distinct geometry and vignetting difference between no lens correction, lensfun, and embedded.

[trougnouf]

Re-tested after ensuring that it compiles on the CI, it still allows for embedded lens corrections :)

[andriiryzhkov]

I tested it on a Sony A7C ARW picture on Arch Linux and it worked well; there is a distinct geometry and vignetting difference between no lens correction, lensfun, and embedded.

Testing note: Sony ARWs are already handled by #21449 (which sets CORRECTION_TYPE_SONY and preserves the SubImage1 tags). Your PR's serializer bails out on its first line for non-DNG correction types, so the corrections you saw round-trip on the Sony A7C are #21449 at work, not this PR.

To exercise this PR's actual code path, source needs to be a file where exif_correction_type == CORRECTION_TYPE_DNG – iPhone ProRAW, Pixel / Samsung Expert RAW, Leica M/Q/SL DNG, DJI drone DNG, Ricoh GR III, or anything through Adobe DNG Converter. If possible please also verify the LinearRaw path (X-Trans) since it also calls the new writer.

[trougnouf]

Sorry about that, I should have tested the master branch first!

[andriiryzhkov]

No problems, and thank you for the contribution. The underlying change is still valid and worth landing. Though it focuses on DNG-source workflows in neural restore module.

[trougnouf]

If possible please also verify the LinearRaw path (X-Trans) since it also calls the new writer.

I confirm that the current master branch supports embedded lens corrections on both the Sony A7C and (X-Trans) Fujifilm X-E2.

No problems, and thank you for the contribution. The underlying change is still valid and worth landing. Though it focuses on DNG-source workflows in neural restore module.

Should I not close this PR then?

[andriiryzhkov]

Should I not close this PR then?

Keep it.