Cache per-frame WCS and aperture geometry for light-curve measurement

[sfoale]

Add FrameGeometry (fits_metadata), built once per frame, holding the cached WCS plus the aperture/annulus radii in pixels, and thread it through _measure_target and measure_candidate_on_frame. WCS builds drop from ~4 per candidate to ~2 per frame.

Testing on the NGC7331 in rp data set on my machine confirmed that the results are identical but run time falls from 72s to 16s.

[Copilot]

Pull request overview

This PR optimizes aperture-photometry/light-curve generation by caching per-frame WCS and pixel-space aperture geometry and by streaming full-resolution pixel data one frame at a time, reducing repeated FITS/WCS work and peak memory usage while keeping outputs identical.

Changes:

• Introduces FrameGeometry (cached WCS + aperture/annulus radii in pixels) and threads it through target/candidate measurement paths.
• Streams SCI pixel data per frame via _load_frame_image / _measure_frame_pixels and adds a downsampled FramePreview for diagnostics overlays (avoids reloading pixels for rendering).
• Adds get_fits_header and updates analysis endpoints/tests to avoid decompressing large compressed SCI images when only metadata is needed.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
datalab/datalab_session/utils/photometry_diagnostics.py	Adds FramePreview + downsampled preview generation; overlays now draw on previews instead of full-res images.
datalab/datalab_session/utils/fits_metadata.py	Adds FrameGeometry and frame_geometry() to cache WCS and pixel radii per frame.
datalab/datalab_session/utils/file_utils.py	Adds get_fits_header() to read headers without forcing SCI decompression; clarifies get_hdu() behavior.
datalab/datalab_session/utils/comparison_stars.py	Refactors comparison selection to operate on pre-measured per-frame measurements; measurement uses cached FrameGeometry.
datalab/datalab_session/utils/centroiding.py	Avoids forced float64 conversion to prevent copying full frames per centroid call.
datalab/datalab_session/utils/aperture_light_curve.py	Major refactor to validate metadata without pixels, then stream per-frame pixel measurement; builds diagnostics previews; reduces CAT-column retention.
datalab/datalab_session/tests/test_operations.py	Updates operation tests for new FileCache usage and generate_light_curve(fits_paths=...) API.
datalab/datalab_session/tests/test_aperture_photometry.py	Updates tests to use FITS paths; adds tests for streaming pixel loading and preview scaling/overlay behavior.
datalab/datalab_session/data_operations/aperture_photometry.py	Resolves FITS paths via FileCache and passes fits_paths into generate_light_curve.
datalab/datalab_session/analysis/wcs.py	Uses get_fits_header() to avoid decompressing SCI image data for WCS inspection.
datalab/datalab_session/analysis/source_catalog.py	Avoids loading SCI pixel data by using get_fits_dimensions() instead of sci_hdu.data.shape.

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[jnation3406]

Looks good other than some duplication of the wcs helper functions. I'm going to merge it into my branch and continue adding to it there.