[agalasso]

indi camera: image format minor refactor

Centralize image format detection and handling at the time the image is
received.

Also, use wxWidgets C-string wrappers for portability.

[agalasso]

@MichaelJEvan please review (github wouldn't let me add you to the list of reviewers)

[MichaelJEvan]

Reviewed and tested on macOS arm64 (native build) with INDI 2.2.2 Guide Simulator + Telescope Simulator:

• .fits (compression off): 120 s guiding, calibration, dither/settle, pause/resume, calibration flip: all pass, no frames lost.
• .fits.fz (compression on, frames ~730 KB vs 2.6 MB): same tests, all pass.
• Unknown format (CCD_TRANSFER_FORMAT = Native, the simulator sends .bin): "Unknown image format: .bin" alert and capture stops, as before.

Code reads fine; bounding the compare by sizeof(bp->format) keeps .fits from matching .fits.fz. One small thing, not blocking: the video-stream path also calls steal(), so each streamed frame now builds an "Unknown image format" message that StackStream doesn't use.

Looks good to me, thanks for the cleanup.

[agalasso]

the video-stream path also calls steal()

@MichaelJEvan Thanks for catching that! I pushed another commit to handle this more gracefully.